Wikipedia talk:Manual of Style/Dates and numbers/Archive 163

External videos
External videos
	"It's called flipping, and it almost oughta be illegal"

This is an archive of past discussions on Wikipedia talk:Manual of Style/Dates and numbers. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page.

Archive 160

Archive 161

Archive 162

Archive 163

Conversion of light years and parsecs

Hi, all. We're trying to harmonize the units used in astronomy articles by building consensus for Wikipedia:WikiProject Astronomy/Manual of Style. It currently seems to be general practice to convert interplanetary distances and smaller to km, but not convert interstellar distances measured in light-years (and to show conversion to parsecs). Given that these units are not used outside astronomy and astrophysics, this contradicts the part of MOS:CONVERSIONS which advises converting "units of measure that are ... obscure outside of a particular specialty or geography". Would it be OK to add an official exception noting interstellar and larger distances should be given in light-years and parsecs and not converted to SI units? -- Beland (talk) 07:11, 23 July 2024 (UTC)

Can you give an example (point to a page) where that conversion to km doesn't happen? Gawaon (talk) 07:15, 23 July 2024 (UTC)

I see that in all the infoboxes of the first extrasolar objects I could think of, namely Alpha Centauri, Betelgeuse, Wolf 359, and Andromeda Galaxy. -- Beland (talk) 07:28, 23 July 2024 (UTC)

Thanks. As someone who's not a editor or expert in the field, but an occasional reader, I'm not in favour. I find 0.024 AU (3,600,000 km) much more helpful than a naked distance in AU, and I find 7.86 light-years (7.44×10¹³ km) more relatable than 7.86 light-years (2.41 parsecs). Light-year and parsec essentially just mean "unimaginably long" to me, but I know what a kilometre is and 10¹³ allows me get a better understanding of the dimensions involved. Gawaon (talk) 09:12, 23 July 2024 (UTC)

Well you're lucky then, because there's no way I'd relate to 10¹³ km in any remotely sensible manner. I can at least think of a light year as about a quarter of the distance to the nearest star to the Sun. Praemonitus (talk) 18:21, 23 July 2024 (UTC)

You quite have a perspective there, because "10¹³ km" is essentially meaningless to me. It is very hard to think about that number in terms of human scale alone. You will not encounter that number on a daily basis except perhaps when discussing countries' GDP or debts.

7.86 light-years (2.41 parsecs) is much more sensible on my perspective. That means light reaches that star in just under 8 years time, and that it makes a parallax angle of 1/2.41ths of an arcsecond every six months in the sky. It is more than just being "unimaginably long." SkyFlubbler (talk) 11:41, 28 July 2024 (UTC)

Would it be better to say that distances given in light-years should only be converted to parsecs and vice versa? Looking at Proxima Centauri and Antares reminds me that distances between binary stars may be appropriately given in smaller units such as AU and billions or trillions of kilometres, which would technically be contrary to an unqualified "interstellar". NebY (talk) 08:47, 23 July 2024 (UTC)

Good point; I mean distances between stellar systems, rather than between stars in the same system. We could say "between stellar systems" or "distances typically measured in light years by reliable sources" to clarify. -- Beland (talk) 16:29, 23 July 2024 (UTC)

No, that would not be OK. That would be like saying it's OK not to convert knots to m/s because nautical people are familiar with knots. What unites all of us is the SI system, so a conversion to SI is needed. Always. Dondervogel 2 (talk) 12:16, 23 July 2024 (UTC)

Would you be in favor of converting from light-years to km only, and dropping parsecs, as in Gawaon's examples above? Parsec says light-year is more common in popular science and general media, which aligns with my experience. I have always found parsecs redundant to light-years and confusingly different. -- Beland (talk) 16:34, 23 July 2024 (UTC)

I would support making a choice between light-years and parsecs (I don't care which, but both would be overkill). Once that choice is made, convert to SI and we're done - in the sense that everyone can then comprehend the distance. Dondervogel 2 (talk) 17:21, 23 July 2024 (UTC)

I agree, that sound reasonable. Among the two, light-year seems to be better known, as Beland noted. Gawaon (talk) 17:26, 23 July 2024 (UTC)

I agree with Dondervogel 2 as well. Avi8tor (talk) 19:56, 23 July 2024 (UTC)

I see little reason not to. Most of the units that aforementioned policy in MOS:CONVERSIONS refer to are still "human-scale", or at least close to it. When one furlong is thrown out, for example, its conversion to 220 yards/0.125 mi/~201 m is easy to visualize, as such lengths are encountered frequently in life. People generally have first-hand experience with distances that long.

One light-year is nearly 1e13 km. I can't speak for everyone, but personally that figure is almost completely meaningless to me; 1e13 km simply is not a comprehensible figure. Even 1 AU (~1.5e11 m) is difficult to comprehend. This is why internet demonstrations of the "true scale" of the Solar System and interstellar space often go viral: people just do not intuitively grasp these distances and scales very well, and no conversion will change that. As Praemonitus mentioned in Wikipedia talk:WikiProject Astronomy/Manual of Style#Conversion of light years and parsecs into km, this issue only gets worse for intergalactic distances on the order of megaparsecs. Ultimately, I fail to see how useful such conversions really would be. ArkHyena (talk) 17:24, 23 July 2024 (UTC)

Thanks for writing this comment, that's precisely my opinion and you saved me the work. Tercer (talk) 17:29, 23 July 2024 (UTC)

I was not aware of this attempt to write a specific MOS for astronomy; I imagine you'd get more informed input at WT:AST than here. Astronomical distances are measured in au within a star/planetary system (including the Solar System), and in parsecs for everything larger (extending to kiloparsecs for galaxies, megaparsecs for galaxy groups etc.). Converting either of those to km would not be useful to readers - the numbers are incomprehensibly vast, which is one of the reasons why astronomers don't use km in the first place. Light years are used only in popular science accounts and press releases, where they do have some utility, but are essentially never the original astronomical measurement. I think it's fine to provide a conversion of pc to ly, but pc should be the primary unit. Converting to km is generally pointless, unless there's some unusual situation. Linking the au or pc unit on first appearance would be more useful to readers. Modest Genius ^talk 17:48, 23 July 2024 (UTC)

PS. There's some relevant discussion in the archives at Wikipedia_talk:WikiProject_Astronomy/Archive_12#Should_we_decide_on_a_default_unit_to_use_across_WP? and Wikipedia_talk:WikiProject_Astronomy/Archive_11#Units_to_be_used_for_distances_and_sizes_in_infoboxes Modest Genius ^talk 17:54, 23 July 2024 (UTC)

The previous discussions linked above seemed to concern whether light-years or parsecs should be used for large distances, and the general consensus seemed to be that astronomers use parsecs, readers are much more likely to understand light-years, and we should just use {{convert}} to display both. That has since at least mostly happened, but no one suggested converting to kilometers, and at that time the language about "obscure outside of a particular specialty" was not in MOS:CONVERSIONS. Hence the current question about resolving the conflict.

Per WP:JARGON, Wikipedia articles are written for the broadest possible audience, and we are advised to "write one level down" if necessary to make technical articles understandable to non-specialists. So if we need to pick two units and one of them is km, then parsecs may have to get the boot because it's mostly only specialists who use them. Fortunately, astronomers should be able to convert from light-years to parsecs easily, unlike the general public, so we don't need to sacrifice level of technical detail.

In other unit-related discussions, we've decided to use {{convert}} to display Wikipedia house style to readers and in some cases hide the units used by sources. Using a parameter like disp=out can do that while preserving the original units for verification against the cited source, and to avoid losing precision if someone comes by later and adds a second conversion. -- Beland (talk) 18:52, 23 July 2024 (UTC)

I disagree, as noted above. 10¹³ km means something to me, even if (admittedly) the dimensions involved are hard to grasp, while throwing "parsecs" or "light-years" around is essentially meaningless. (I agree one of them should be used too, but not exclusively.) Gawaon (talk) 18:16, 23 July 2024 (UTC)

I wonder then how many lay readers are familiar with distances expressed in exponential notation? Because that isn't everyday usage. If you saw 1×10¹³ in a lay readers article, it would be more likely to be written as "10 million million kilometers". I look at the public facing NASA article The Galaxy Next Door and it gives distances and dimensions in light years, so NASA is expecting the public to be familiar with that distance scale. The distance to the Andromeda Galaxy is something like "25 million million million kilometers", surely a cumbersome statement. Praemonitus (talk) 22:01, 23 July 2024 (UTC)

I must agree with this, I—anecdotally—would not expect most laypeople to understand what 1e13 km really means. To my knowledge, most educational platforms do not convert lyr or pc to km/mi (some examples: [1] [2] [3] [4]). It is clear that science communication as a whole deems conversions of lyr into km/mi as unhelpful and unneeded for most purposes. ArkHyena (talk) 22:20, 23 July 2024 (UTC)

I checked my state's curriculum standards, and exponential notation is required to be learned in eighth grade. So I would guess this has been taught to anyone who has completed their primary school education in a country with a decent education system. That doesn't include all our readers, and some people will have failed math or completely forgotten this concept. On radio broadcasts for popular consumption, I have definitely heard constructions like "billion billion" or "6 with 20 zeroes after it" in lieu of exponential notation, and also light-years.

Based on editors' personal reports here, it seems there are some people who think in light years and some who think in large numbers of kilometers. Why not have both to maximize accessibility and intuitive understanding? Anyone who knows what a parsec is almost certainly has a firm grasp on what a light-year is. -- Beland (talk) 22:38, 23 July 2024 (UTC)

The issue is that there are situations where this may introduce clutter with arguably marginal benefit, especially in infoboxes. I suppose introduction of conversion in main article text is fine, so long as km values are given in exponential notation to limit clutter. A potential compromise would be to add a note upon first mention of a lyr/pc in an article that provides km values for one lyr/pc; this is broadly similar (though not perfectly analogous) to how hurricane articles handle major hurricane status (e.g. at Hurricane Beryl). ArkHyena (talk) 23:27, 23 July 2024 (UTC)

That's an interesting idea...you're thinking light years converted to parsec in infoboxes, light-years converted to kilometers in article prose (and maybe only at first mention)? -- Beland (talk) 04:47, 24 July 2024 (UTC)

I'm opposed to the latter. If we're expecting students to know what a kilometre is and to grok out exponential notation, then it's reasonable to expect that they will also understand a light year. I see no need to provide a conversion to km in most cases. A link should suffice. Praemonitus (talk) 14:47, 24 July 2024 (UTC)

What do you mean with "understand" here? I know what a light-year is, in the abstract sense: It's the distance light travels in a year. And I, and guess most people, also know that light travels "very fast". But how much is "very fast" times one year? I don't have the foggiest idea, to be honest. Never having travelled at the speed of light, it is very hard to fathom for me, and as such essentially meaningless. Exponential notation, on the other hand, is not very hard to get, if you know how to do basic addition and multiplication. If I read 10¹³ km, I know I have to take one kilometre, multiply it with 1000, and again, and again, and again, and then finally with 10. Still abstract, admittedly, but now I have a much better sense of the dimension involved compared to "unimaginably fast times one year". Which is why I'm in favour of using exponential notation in addition to light-years or parsecs (I don't care which of them is chosen). Gawaon (talk) 15:09, 24 July 2024 (UTC)

I would perhaps prefer 10 Pm to 10¹³ km, but other than this detail I strongly agree with Gawaon. I can accept 10¹³ km if that is the consensus. I cannot accept omitting the conversion to SI - to do so would suggest that astronomy is beyond metrology, when it clearly is not. Notice the link to petametre takes the reader directly to an equation stating that a petametre is about 0.1 light-year. Dondervogel 2 (talk) 15:20, 24 July 2024 (UTC)

Oh come on. It suggests nothing of the sort (about astronomy being beyond metrology). Metrology is a whole discipline; SI is just a system of units, roughly as arbitrary as any other.

That said, I don't have a hardened objection to including an SI conversion, at least in infoboxes, though I wouldn't be thrilled to see them repeated over and over again in the running text. --Trovatore (talk) 16:18, 24 July 2024 (UTC)

OK, so I was exaggerating, for effect. A more measured remark would have been that even the IAU defines its units in terms of the SI, so why mark it unnecessarily hard on the reader by omitting that conversion on Wikipedia? I accept the SI is arbitrary, but it is THE single arbitrary system that we all (including Americans) learn at school, is used in day to day scientific work and is defined by international standards (BIPM).

Providing a conversion to SI in info boxes seems a good compromise. Dondervogel 2 (talk) 18:47, 24 July 2024 (UTC)

I would argue for the inverse, actually. Providing SI conversions in maintext whilst omitting them in infoboxes seems to be the best practice besides not having any. Infoboxes, especially those of astronomy, are already crowded with numbers; it would not help readability to shove yet more in them. ArkHyena (talk) 18:55, 24 July 2024 (UTC)

Right now light-years and parsecs are typically presented side-by-side in infoboxes. If one of them is replaced with a different unit, that wouldn't result in any additional clutter. Gawaon (talk) 19:04, 24 July 2024 (UTC)

Per SevenSpheres: The astronomical literature almost exclusively uses parsecs, because distance in parsecs can be derived directly from parallax, which is used to measure stellar distances. So it makes sense to use both units. I don't think I've seen interstellar distances expressed in kilometers much if at all before today ... On the topic of deriving distance from parallax, {{Starbox astrometry}} can do this automatically and is used this way in most star articles. So even if parsecs aren't used in the text, it doesn't make sense to remove them from the infobox

If we are to implement SI conversions, they are better-suited for the maintext (either as first mention or throughout), since that is presumably where most readers read. Astronomy infoboxes typically hold information about more obscure/technical (even if still very much relevant) properties for their respective objects. ArkHyena (talk) 19:32, 24 July 2024 (UTC)

"So I would guess this has been taught to anyone who has completed their primary school education in a country with a decent education system." - And most people don't work in science-related fields, and so never use scientific notation and thus have forgotten it. "10^13 km" and "1 light year" both translate to "very, very large", but the latter can at least allow comparison of distances--"it's only a few light years to the nearest star, but a million light years to the nearest galaxy."--whereas 10^13 km and 10^19 km are both equally meaningless as "very large", because they don't think in subtracting exponents. The prefixes are even worse, as anything beyond giga or tera are completely unfamiliar to most (and even those just mean "big" to many). - Parejkoj (talk) 06:50, 25 July 2024 (UTC)

No one is suggesting we stop using light-years (or parsecs if you prefer those - take your pick). We just prefer to include a conversion to SI, because we are all taught SI units. It's called the International System of Units for a good reason. Dondervogel 2 (talk) 07:08, 25 July 2024 (UTC)

I disagree. In this field of astronomy the governing body would be the International Astronomical Union, and the SI would only be focused on standardizing units relevant to common everyday measurements (and perhaps those in technology). And parsec is specifically defined in the notes of Resolution B2 in 2015. SkyFlubbler (talk) 12:02, 28 July 2024 (UTC)

Not everybody is an astronomer though, and our articles shouldn't be accessible to specialists only. Gawaon (talk) 12:58, 28 July 2024 (UTC)

But this is still a topic of astronomy, so of course we have to use units used by astronomers. By your logic we should not use radians as an angle measurement despite countless mathematical areas using it because "not everybody is a mathematician."

If they are seeking astronomy topics here in Wikipedia, the article for parsec is as simple as a mouse click. SkyFlubbler (talk) 23:31, 30 July 2024 (UTC)

In general, we don't use radians for angles, such as when discussing bicycle frames or sports or flowers). We use the much better-known degrees, unless there is a specific reason that radians make calculations or geometric expressions easier (which is why they exist). Radians are also much better-known than parsecs. I checked the Massachusetts curriculum standards; radians are part of the secondary school math requirements. Parsecs are not a requirement, and I would expect them to be first taught in undergrad astronomy classes (which obviously hardly anyone takes, though I did) or picked up as an extracurricular interest.

Certainly linking unfamiliar units like parsecs helps a lot of readers make more sense of them, but not everyone using Wikipedia has a mouse. Sometimes articles are printed out. Sometimes they are read out loud by a text-to-speech system - quite common for blind and visually impaired people, and also among people like me who use TTS to read articles while doing something else like yard work or doing the dishes. All of us screenreader users potentially have to listen to conversions for every single field in an infobox, which can get a bit tedious and make things harder to follow, especially if we don't know the definition of one of the units. -- Beland (talk) 02:55, 31 July 2024 (UTC)

What do you mean by "your logic"? I'm in favour of using parsecs, but against using only parsecs (or only non-SI units). Gawaon (talk) 05:58, 31 July 2024 (UTC)

This astronomy MOS was announced at WT:AST and considerable discussion has already happened there, and I already posted there a link to this discussion. I started this discussion because I wasn't comfortable creating an exception to MOS:CONVERSIONS without consulting the wider editor community beyond the WikiProject Astronomy. -- Beland (talk) 18:31, 23 July 2024 (UTC)

Light-years are not an obscure or specialized unit; along with parsecs, they are the standard units used to measure interstellar and larger distances. While it's true that they're only used in one field, astronomy is the only field that deals with such large distances! This is different from, say, furlongs, which are on the same scale as kilometers.
My thought is that interstellar distances expressed in kilometers are meaninglessly large numbers, while such distances expressed in light-years are more accessible to the general reader. Surprisingly though, there are comments saying the opposite! I find it hard to believe this is representative of the average reader though; surely most people who understand scientific notation also understand what a light-year is? That if a star is 100 light-years away, its light takes 100 years to reach us and so we see it as it was 100 years ago?
In terms of common usage, sources aimed at the general public (like the NASA pages linked above) almost exclusively use light-years, presumably because, again, this is the most accessible unit to the general public. The astronomical literature almost exclusively uses parsecs, because distance in parsecs can be derived directly from parallax, which is used to measure stellar distances. So it makes sense to use both units. I don't think I've seen interstellar distances expressed in kilometers much if at all before today.
- (On the topic of deriving distance from parallax, {{Starbox astrometry}} can do this automatically and is used this way in most star articles. So even if parsecs aren't used in the text, it doesn't make sense to remove them from the infobox.)
A proposed change of this kind that would affect so many articles should be more widely advertised; I suspect everyone who's commented here watches either this page and/or WikiProject Astronomy where this was mentioned.

SevenSpheres (talk) 00:21, 24 July 2024 (UTC)

If we decide to suppress parsecs from reader view, {{Starbox astrometry}} can simply be changed to convert to light-years or whatnot. It's actually a lot easier to do that than change 1,000 articles that are not using a template feature like that, which I am sadly already doing for a lot of problems. -- Beland (talk) 04:51, 24 July 2024 (UTC)

There's no way a light-year is a standard unit. It is not defined by international standards bodies, and according to the IAU, light-years are "mostly confined to popular publications and similar media". And I suspect there are more readers who think the light-year is a unit of time than ones who would be confused by use of the metre (or kilometre) as a unit of distance. If there is a standard unit in astronomy, it is the parsec, not the light-year. Dondervogel 2 (talk) 11:21, 24 July 2024 (UTC)

I don't there exists anyone who thinks light-year is a unit of time but understands what a parsec is. Ironically enough, the creators of Star Wars thought parsec was a unit of time. Tercer (talk) 12:32, 24 July 2024 (UTC)

@SevenSpheres: FYI 1 furlong is 201.168 m, so not quite the "same scale". Martin of Sheffield (talk) 14:14, 24 July 2024 (UTC)

Corrected. SevenSpheres (talk) 15:10, 24 July 2024 (UTC)

Where would you like to see this discussion "more widely advertised"? -- Beland (talk) 15:57, 24 July 2024 (UTC)

WP:RFC? SevenSpheres (talk) 16:16, 24 July 2024 (UTC)

If we're doing that, we should summarize the discussion into some clear options. How about this for a question with neutral background material:

----

How should distances between stellar systems and longer be presented in infoboxes? (These are often calculated automatically from different units presented in astronomy sources, such as parallax.)

Examples from Local Interstellar Cloud, Andromeda Galaxy, Proxima Centauri, and Betelgeuse.

A.) Light-years and kilometers only in infoboxes:

30 ly (2.8×10¹⁴ km)
2.50 Mly; 2.36×10¹⁹ km
4.2465 ± 0.0003 ly
4.0175×10¹³ ± 2.8382×10⁹ km
408–548+90
−49 ly (3.86×10¹⁵–5.18+0.85
−0.46×10¹⁵ km)

B.) Light-years and parsecs only in infoboxes

30 ly (9.2 pc)
2.50 Mly; 765 kpc
4.2465 ± 0.0003 ly
1.3020 ± 9.1980×10⁻⁵ pc
408–548+90
−49 ly (125-168.1+27.5
−14.9 pc)

C.) Light-years and meters with larger prefixes in infoboxes

30 ly (280 Pm)
2.50 Mly; 23.6 Zm
4.2465 ± 0.0003 ly
40.1750 ± 0.0028 Pm
408–548+90
−49 ly
3.86–5.18+0.85
−0.46 Em

D.) Light-years and parsecs only in infoboxes (like B), with conversion to kilometers on first mention in prose

E.) Something else

If conversion to kilometers in infoboxes is not required, this would be added as an explicit exception to MOS:CONVERSIONS.

Previous discussions identified that parsecs are used by professional astronomers and light-years are used in popular news and educational media. Editors disagreed on whether light-years or kilometers with exponential notation were easier to read and understand intuitively for most readers.

----

-- Beland (talk) 18:10, 24 July 2024 (UTC)

(Edited to link units.) -- Beland (talk) 18:16, 24 July 2024 (UTC)

How about "Parsecs and kilometers only in infoboxes" as further option, since that combination has been mentioned as well? Also, if you suggest 5 or 6 different options, it's quite likely that none of them will gain an absolute majority, resulting in an unclear outcome.

An alternative question might be something along the lines of "Since it's cumbersome to present more than two alternative units, which two should preferably to used for interstellar distances?", with the options being:

A. Light-year

B. Parsec

C. Kilometre with exponential factor

D. Metre with SI prefix

And every editor asked to pick their two favourites. Gawaon (talk) 18:54, 24 July 2024 (UTC)

OK, maybe we should ask the "pick two" separately for prose and infoboxes, since there seems to be a stronger leaning toward different practices, and it would be nice to get a clear result for both if we're bothering everyone to consider the question. -- Beland (talk) 22:02, 24 July 2024 (UTC)

Okay, why not, though personally I see no good reason to treat them differently. Gawaon (talk) 06:11, 25 July 2024 (UTC)

Some editors have expressed different preferences for prose vs. infobox...at this point I've thought about all this too much and don't know how I feel about anything. Revised draft RFC posted in subsection below; everyone feel free to tweak or critique. -- Beland (talk) 07:32, 25 July 2024 (UTC)

If you're referring to my comment, I haven't expressed different preferences for prose vs. infobox, only a stronger preference to retain the status quo in infoboxes. SevenSpheres (talk) 14:55, 25 July 2024 (UTC)

I was thinking of ArkHyena's proposal to convert to km on first mention in prose but not infoboxes. -- Beland (talk) 19:48, 25 July 2024 (UTC)

IAU definitions are about as standard as you're going to get in astronomy. Per the IAU style manual, the "unit known as the light-year is appropriate to popular expositions on astronomy and is sometimes used in scientific papers as an indicator of distance".[5] "The light-year is roughly equivalent to 0.3 parsecs, and is equal to the distance traveled by light in one Julian year in a vacuum, according to the IAU."[6] The parsec does have a standard IAU definition, although it is a much less well known unit in the public space. Praemonitus (talk) 14:54, 24 July 2024 (UTC)

Looking again at MOS:CONVERSIONS, I think In some topic areas [...] it can be excessive to provide a conversion for every quantity applies here, though unlike light-years the examples given are at a scale where metric units are typically used. As I've said, I don't think For units of measure that are [...] obscure outside of a particular specialty or geography applies; not part of the SI or US customary systems may apply but that's not the part that was mentioned. SevenSpheres (talk) 18:22, 24 July 2024 (UTC)

Are you arguing for leaving some quantities in infoboxes unconverted from the preferred unit, or are you thinking of omitting conversions only in prose? -- Beland (talk) 18:39, 24 July 2024 (UTC)

The opposite, as per e.g. [7] I would more strongly prefer to retain the status quo in infoboxes than in prose. SevenSpheres (talk) 19:03, 24 July 2024 (UTC)

OK, that looks like a vote for light-years and parsecs in infoboxes with kilometers in prose but not to excess. I consider the status quo to be "SI conversions are required in infoboxes" because of MOS:CONVERSIONS, but in practice for the ones I've seen, the status quo is light-years and parsecs. -- Beland (talk) 22:01, 24 July 2024 (UTC)

All I will say is that this discussion seems to connect with the one I began about prefixes. Looking at this thread it seems I might not be alone here. Avenues2009 (talk) 23:18, 29 July 2024 (UTC)

Sure; feel free to share your preferences in the RFC thread. -- Beland (talk) 01:19, 30 July 2024 (UTC)

Draft RFC question

Version 1

How should distances between stellar systems and longer be presented in astronomy articles? (These are often calculated automatically from different units presented in astronomy sources, such as parallax.) Previous discussions identified that parsecs are used by professional astronomers and light-years are used in popular news and educational media; those two units are currently the most commonly used and converted to each other. Editors disagreed on whether light-years or kilometers with scientific notation were easier to read and understand intuitively for most readers. If conversion to SI units (like kilometers) is not required in certain contexts, this would be added as an explicit exception to MOS:CONVERSIONS.

More than two units per quantity is cumbersome, so we're asking folks to pick their TOP TWO from:

Infobox examples using quantities from Local Interstellar Cloud, Andromeda Galaxy, Proxima Centauri, and Betelgeuse:

ly and km:
- 30 ly (2.8×10¹⁴ km)
- 2.50 Mly; 2.36×10¹⁹ km
- 4.2465 ± 0.0003 ly
  4.0175×10¹³ ± 2.8382×10⁹ km
- 408–548+90
  −49 ly (3.86×10¹⁵–5.18+0.85
  −0.46×10¹⁵ km)
ly and pc:
- 30 ly (9.2 pc)
- 2.50 Mly; 765 kpc
- 4.2465 ± 0.0003 ly
  1.3020 ± 9.1980×10⁻⁵ pc
- 408–548+90
  −49 ly (125-168.1+27.5
  −14.9 pc)
ly and ?m:
- 30 ly (280 Pm)
- 2.50 Mly; 23.6 Zm
- 4.2465 ± 0.0003 ly
  40.1750 ± 0.0028 Pm
- 408–548+90
  −49 ly
  3.86–5.18+0.85
  −0.46 Em

Please let us know if you prefer the SAME or DIFFERENT for INFOBOXES vs. PROSE (or if you prefer some other solution). We assume that for prose the "unless this would be excessive given the context" rule from MOS:CONVERSIONS will still apply.

Version 2

How should distances between star systems and galaxies be presented? These are measured in light years (ly) in popular news and educational media; professional astronomers use parsecs (pc). Articles currently use a variety of units (some only ly and ly converted to km) but most commonly use ly converted to pc in infoboxes (often automatically from technical data). If conversion to SI units (like kilometers) is not required in certain contexts, this would be added as an explicit exception to MOS:CONVERSIONS. The maximum distance in the observable universe is under 100 billion light-years, and interplanetary distances (inside a star system) are a fraction of a light-year and are measured in astronomical units (AU or au).

Two formats are needed: an expanded format for use in article prose (especially on first mention), and a compact format for infoboxes, tables, and prose where the expanded format would be excessively long. The "unless this would be excessive given the context" rule from MOS:CONVERSIONS will still apply when the units are used several times in prose.

The units nominated in previous discussion are:

Light-year (ly)
Parsec (pc)
Kilometer (km)
Meter (m)

Units can be written in words or symbols, but if symbols are used, MOS:NUMNOTES says the number part must be written in numbers (e.g. 12 million km, not twelve million km). First use of light-year/ly and parsec/pc must be linked to their articles, per MOS:UNITS.

The notations that can express very large quantities are:

Words (million, billion, trillion, and so on in names of large numbers)
Metric prefixes, namely: Gly, Mly, kly, Gpc, Mpc, kpc, Ym, Zm, Em, Pm, Tm
Scientific notation, often used with km (which already have a metric prefix), e.g. 8.8×10²⁰ km
Long numerals, e.g.: 93,000,000 ly (88,000,000,000,000,000,000 km)

Formatting details are delegated to {{convert}} and {{val}}, which may be helpful in expressing your preferences below.

The chosen formats need to accommodate simple cases and complex expressions of precision like:

30 ly (2.8×10¹⁴ km)
2.50 Mly (765 kpc)
4.2465 ± 0.0003 ly
4.0175×10¹³ ± 2.8382×10⁹ km
408–548+90
−49 ly (125-168.1+27.5
−14.9 pc)

Please specify which order the units should appear in, if you have a preference.

(sample votes shown)

Compact format (specify preferred units, notation, and order)

ly only, with metric prefixes. "34.5 Mly ± .3Mly". Infoboxes get overwhelmingly numbery if they have conversions. - User 1
ly converted to pc, both in exponential notation. "34.5×10⁹ ly (1.06×10¹⁰ pc)". Astronomers need parsecs for convenience. - User 2

Expanded format (specify preferred units, notation, and order)

"Light year" converted to km, in exponential notation. "34.5 million light years (3.26×10²³ km) " - User 1
"Light years" converted to "kilometers" then "parsecs", in words, but no higher than trillion. "34.5 million light years (326 billion trillion kilometers; 10.6 billion parsecs) plus or minus .3 million light years." - User 2

Version 3

What units should be used for distances between star systems and galaxies? These are measured in light years (ly) in popular news and educational media; professional astronomers use parsecs (pc). Articles currently use a variety of units (some only ly and some ly converted to km) but most commonly use ly converted to pc in infoboxes (often automatically from technical data). If conversion to SI units (like kilometers) is not required in certain contexts, this would be added as an explicit exception to MOS:CONVERSIONS. The maximum distance in the observable universe is under 100 billion light-years, and interplanetary distances (inside a star system) are a fraction of a light-year and are measured in astronomical units (AU or au).

Two formats are needed: an expanded format for use in article prose (especially on first mention), and a compact format for infoboxes, tables, and prose where the expanded format would be excessively long. The "unless this would be excessive given the context" rule from MOS:CONVERSIONS will still apply when the units are used several times in prose. First use of light-year/ly, parsec/pc, and rare meter prefixes (e.g. zettameter) must be linked to their articles, per MOS:UNITS. The chosen formats need to accommodate simple cases and complex expressions of precision (examples below).

The choices nominated for inclusion are:

Light-year (ly) with SI prefixes (kly, Mly, Gly) and large number words (million, billion) in prose
- 34.6 ± 0.3 million light-years (ly) [first mention in prose]
- 34.6 ± 0.3 Mly [compact]
- 408–548+90
  −49 ly [compact]
Parsec (pc) with SI prefixes (kpc, Mpc, Gpc)
- 765 ± 2 kiloparsecs (kpc) [first mention in prose]
- 765 ± 2 kpc [compact]
- 125-168.1+27.5
  −14.9 pc [compact]
Kilometer (km) with scientific notation
- 3.27×10¹⁴ km [compact, secondary in prose]
- 3.273×10¹⁴ ± 2.8×10¹² km [compact, secondary prose]
- 68.1+7.5
  −4.1×10¹⁴ km [compact, secondary in prose]
- 3.27×10¹⁴ kilometres [primary expanded]
Meter with SI prefixes (Ym, Zm, Em, Pm, Tm)
- 68.1 zettameters (Zm) [first mention in prose]
- 68.1 Zm [compact]
- 68.1+7.5
  −4.1 Zm [compact]

You can of course advocate for as many or few options as you find appropriate, or assert multiple options are equally good, but previous discussion has assumed at most two units would be used because many editors find three to be excessive. Please specify your preferred order; "primary" units come first and other units are converted to (typically in parentheses in prose, sometimes on a new line or after semicolon in infoboxes).

(sample votes shown)

Your preferred units

Please note your preferred units for both compact-in-infobox and expanded-in-prose if they are different.

Light-years only. Conversions make science overwhelmingly numbery. - User 1
Light years converted to parsecs in infoboxes for astronomers, kilometers in prose for general audience. - User 2

Discussion

For clarity I would suggest using the same format for all examples (always put the second unit in brackets or maybe always use a semicolon between them, instead of semicolons, brackets, and line breaks mixed). Otherwise it looks fine to me. Gawaon (talk) 08:07, 25 July 2024 (UTC)
I'm afraid it's hard to decipher your illustrative possibilities; I think it's better to say explicitly that you are displaying the same data using the three combinations (ly, km), (ly, pc), and (ly, ?m). Also, it might be worth noting that (ly, pc) is already a de facto standard. Tercer (talk) 08:35, 25 July 2024 (UTC)
Tweaked to add headers for clarity. -- Beland (talk) 09:27, 25 July 2024 (UTC)
And added note about the status quo in articles, per your suggestion. -- Beland (talk) 09:28, 25 July 2024 (UTC)

In articles, I see semicolons, parentheses, and new lines in infoboxes. -- Beland (talk) 09:24, 25 July 2024 (UTC)

Okay. Gawaon (talk) 10:28, 25 July 2024 (UTC)

I have two comments

I object to using megalight-years in the examples. While light-years are commonly used, megalight-years are not (and the unit in any case should be light-megayear, not megalight-year). Saying "2.5 million light-years" is fine. Saying "2.5 megalight-years" is not.
I'm not sure the question is well posed. Surely we are all assuming the primary unit is either light-year or parsec, and the question should then be "what are converting it to?"

Dondervogel 2 (talk) 09:59, 25 July 2024 (UTC)

That's not true. Mly is commonly used. "light-megayear" is non-existent. Tercer (talk) 10:31, 25 July 2024 (UTC)

I meant that in a relative sense. In other words, use of the megalight-year is less common than that of the light-year. I accept that light-megayear is rarely used, but if one uses light-second, light-minute, light-day and light-year, the obvious next steps are light-century, light-kiloyear and light-megayear. That was my point.

That said, my main objection to use of megalight-year, gigalight-year is the absence of an authoritative/standard definition of these units. The IAU does not define them, so who does? Perhaps the same question applies to the megaparsec, but that seems somehow less controversial. I'm not sure why. Dondervogel 2 (talk) 16:44, 25 July 2024 (UTC)

I'd say if Mly is used in existing pages, it's okay to use it in an example too. Gawaon (talk) 17:36, 25 July 2024 (UTC)

I mean, why would the IAU have to define them when mega- and giga- prefixes are already well-defined? This doesn't seem to be a very good justification to not use them; AFAIK, no organization "officially defines" what a kiloton or megaton is, but articles about nuclear tests and volcanic eruptions use them all the time in TNT-equivalent units simply because kt and Mt are useful and widely used. ArkHyena (talk) 17:40, 25 July 2024 (UTC)

I'll pay you 10€ if you can find a single example of light-megayear used in a peer-reviewed paper. I see your point about the logical progression of the units, but the fact of the matter is that this is not how astronomers use it. Tercer (talk) 17:54, 25 July 2024 (UTC)

Hmmm ... that's an interesting challenge. I can't guarantee to find light-megayear, but I would be surprised if a search for light-kiloyear, light-megayear and light-gigayear doesn't come up with something. Watch this space ... Dondervogel 2 (talk) 19:20, 25 July 2024 (UTC)

... I found this mention of a light-gigayear. See also [8] Project Astronomy Archive 17, where it appears the same question arose 9 years ago, and with the same outcome. Dondervogel 2 (talk) 19:37, 25 July 2024 (UTC)

Light-gigayear is fair enough, but I did specify a peer-reviewed paper. Tercer (talk) 20:08, 25 July 2024 (UTC)

You did indeed, so I am not claiming my 10 EUR just yet. I'll keep watching out for an example :P Dondervogel 2 (talk) 20:13, 25 July 2024 (UTC)

It just dawned on me that the reason I can't find light-megayear in peer-reviewed papers is that peer-reviewed papers use the parsec (and megaparsec), not the light-year. The light-year is used in popular literature only, where it does not need a rigorous definition. Perhaps that explains why Mpc seems less controversial (to me) than Mly. Dondervogel 2 (talk) 20:23, 25 July 2024 (UTC)

While parsecs are clearly the unit of choice, plenty of peer-reviewed astronomy papers do use light-years: [9] [10] [11]. Tercer (talk) 20:44, 25 July 2024 (UTC)

Sometimes I really do wish astronomers and science communicators would use just one unit instead of two... ArkHyena (talk) 20:50, 25 July 2024 (UTC)

Yes, I see those articles use the light-year (though in one case only in the title). Do you know one that uses the megalight-year? Dondervogel 2 (talk) 20:56, 25 July 2024 (UTC)

It looks like Morrison and Sartori 1965 might use the light-kiloyear. I can't be sure because it's behind a paywall. Does anyone have access to Phys Rev Lett? Dondervogel 2 (talk) 21:19, 25 July 2024 (UTC)

I found it and yes, they talk about "R ~ 10 light kiloyears". Gawaon (talk) 22:07, 25 July 2024 (UTC)

I have checked, and indeed, that's a light kiloyear. Not a light-megayear, but I think it's good enough. Please email me your IBAN through Special:EmailUser/Tercer so that I can pay you what I owe. Tercer (talk) 08:33, 26 July 2024 (UTC)

Light-year#Definitions has citations to textbooks for kly, Mly, and Gly, kilolight-year, megalight-year, and gigalight-year. English isn't always a logical or consistent language, but we use it as it is. There doesn't seem to be any disagreement about what these units mean; they adopt the SI prefixes straightforwardly. Mly, Gly, kpc, and Mly are currently used in a lot of articles, but I also see constructions like "70,000,000 ly" in infoboxes and "70 million light years" in prose. These units are a lot more compact and a lot cleaner when there are ±, and they have commonly-used prefixes people are familiar with from computer hardware. Beland (talk) 17:56, 25 July 2024 (UTC)

We can ask this question two ways: 1. pre-discuss possibilities and offer up the most popular (among astro-enthusiast editors) and logically coherent choices in an effort to make the question easy to answer and consensus easy to discern, or 2. open voting to arbitrary combinations and have faith that The People will Do the Right Thing. I started with approach 1, but Gawaon requested approach 2. If we're sticking with approach 2, I'm inclined to let the wisdom of the crowd decide which unit they want as primary. If 70% of people vote to make kilometers primary, then that's surprising but useful information to make the encyclopedia more readable to the general public, and no one can complain the question was biased and we need to do another RFC. We've been talking about two units of measure as the optimal number, but the more articles I look at, the more I wonder if 1 or 3 wouldn't be better, depending on whether we want to make things clear and easy to understand (which some articles already do) or give everyone immediate handy access to a number in the units they are thinking or calculating in.

I was originally thinking of this only as a question for infoboxes, but the more articles I look at, the more I realize that quantities are presented very differently in prose. For example, "72 million light-years" is much more reader-friendly than either "7.2 × 10⁶ ly" or "7.2 Mly", and the friendly version is often used in prose. Perhaps we should frame the question as asking people to define "compact" and "expanded" formats. In prose, we often use an expanded format on first mention of an unfamiliar-to-everyday-life unit (like light-years), and then compact formatting for later uses to avoid excessive length. We also use compact formats for tables, not just infoboxes. MOS:NUMNOTES has some things to say about this already, but doesn't make all the choices we have questions about.

When we write $2M in prose, we write two million dollars, not two megadollars, and I agree 2Mly should be written as two million light years, megatons notwithstanding. I'll add some prose examples showing the default interpretation of choosing certain units. Beland (talk) 18:23, 25 July 2024 (UTC)

I didn't mean to ask about "primary" and "secondary", only about the preferred combinations of two units (considering that regularly using more would be impractical). I think the only truly "odd" result from the astronomers' viewpoint would be if kilometres and prefixed metres were chosen, with both light-years and parsecs discarded. But I think that's a very unlikely outcome, hence I believe we can trust the "wisdom of the crowd" to find a reasonable combination. Gawaon (talk) 19:08, 25 July 2024 (UTC)

(Also I didn't mean to "request" anything, it was just a suggestion to make the multiple logical possibilities easier to handle.) Gawaon (talk) 19:12, 25 July 2024 (UTC)

Sure, it was a good suggestion! BTW, I've drafted a second version of the RFC question making the variables more explicit and connecting to some existing rules so hopefully we don't have to re-debate those. Too much? -- Beland (talk) 19:37, 25 July 2024 (UTC)

@Beland: I question the assertion that there is no dispute about the meaning of megalight-year. According to this unit converter, a megalight-year is equal to 999315.53730322 light-years. Is that the conversion you would expect? Dondervogel 2 (talk) 19:25, 25 July 2024 (UTC)

Seems like a floating point error. SevenSpheres (talk) 19:35, 25 July 2024 (UTC)

I doubt it's a floating point error. More likely a consequence of the ambiguity between a megaannum (precisely 365.25 million days, following the IAU convention, using Julian years) and one million years (approximately 365.2422 million days). I don't think the arithmetic works out to explain that weird conversion, but my fundamental point is that such units are undefined, and therefore ambiguous. Dondervogel 2 (talk) 19:52, 25 July 2024 (UTC)

This website is clearly suffering from rounding errors. It converts 9999999999999 mm to 9999.999999999001 Mm. It's pretty clearly a not-so-carefully semi-automatically created SEO honeypot. -- Beland (talk) 19:56, 25 July 2024 (UTC)

Somebody used "365.5" when entering one unit into the database, and "365.25" for the other: 999315.53730322 / 365.25 = 365.5×10⁻⁶. Indefatigable (talk) 19:58, 25 July 2024 (UTC)

Nice catch! Tercer (talk) 20:11, 25 July 2024 (UTC)

...hmm, it does actually say that in the text though... but it also says One megalight-year [...] is one million light-years. That website is probably not the most reliable source in any case. SevenSpheres (talk) 19:37, 25 July 2024 (UTC)

Shitty websites making mistakes prove nothing. If you want to demonstrate that there is a dispute about the definition of megalight-year you need to find reliable sources saying so. Tercer (talk) 19:50, 25 July 2024 (UTC)

Uh-uh. The unit remains ambiguous until it is defined. And there is never a justification for using this particular ambiguous unit when we can easily write "one million light-years", with no ambiguity. Dondervogel 2 (talk) 19:54, 25 July 2024 (UTC)

I fail to see how "megalight-year" would remotely be ambiguous, unless the metric prefix "mega-" itself is ambiguous. ArkHyena (talk) 20:01, 25 July 2024 (UTC)

But the prefix mega- (as in megabyte) IS ambiguous. I suspect you realised that before adding the "metric" qualifier. For the definition we rely on a handful of sources from the light-year article. Is that really enough? And I repeat we can always write "one million light years" (or "one billion light years" for giga), so why confuse our readers with the prefix? Dondervogel 2 (talk) 20:10, 25 July 2024 (UTC)

That particular case is does seem to be exceptional due to its usage within compsci, but honestly I doubt people who are aware of that oddity would apply it to other units. "Mega-", regarding units, seems to be universally understood to mean 10⁶ unless specified otherwise, regardless if the unit it is applied to is SI or not. A megatonne of TNT equivalent is one million tonnes of TNT equivalent. A megaelectronvolt is one million electronvolts. And so on.

The one possible point of confusion is that "mega-" in colloquial usage does not strictly refer to the metric prefix, e.g. "megadonor", but TMK people generally recognize that, when affixed to a unit of measurement, "mega-" indeed means 10⁶. ArkHyena (talk) 20:22, 25 July 2024 (UTC)

Can we agree to write "6.7 million light years" instead of "6.7 mega-light-years" and "9.8 megaparsecs" (which seems standard) and 6.7 Mly and 9.7 Mpc for short? I don't think anyone is going to be confused into thinking that the "M" uses the 1000x scale instead of 1024x for light years but not parsecs. Certainly not people who know enough to need the numbers for precise calculations, who seem to be using Mly in technical papers with zero confusion. 1000x is what everyone in America is taught in school when we learn the metric system. Almost anyone who knows about the 1024x scale should know it's only used for computers. Our main audience is the general public to whom we're giving these numbers just to get a general sense of things (at which point 1000x vs. 1024x doesn't matter). -- Beland (talk) 22:19, 25 July 2024 (UTC)

Reliable sources do define Mly as exactly one million light-years, as cited at light-year. Definitions of units don't need to be blessed by a government or professional body to have a clear meaning, any more than "straight up" needs an English equivalent of the French Academy to legally define which vector I mean by that. This web site is unambiguously making an error. -- Beland (talk) 20:01, 25 July 2024 (UTC)

Since some votes will differ in options for infobox vs. prose (or some contributors may want to add notes specific to one or the other), it may be best to set up two separate surveys (e.g. survey for infoboxes/survey for prose) once the RfC is pushed out for organizational reasons. ArkHyena (talk) 10:56, 25 July 2024 (UTC)
Excellent suggestion; implemented in Version 2 of the draft above. -- Beland (talk) 19:38, 25 July 2024 (UTC)
My preference (and I don't think I am alone here) would be
primary unit: parsec or light-year

converted unit: any SI unit
I don't see this preference represented in the choices offered. Dondervogel 2 (talk) 19:59, 25 July 2024 (UTC)
That seems like a perfectly valid not-vote. We didn't say you couldn't pick multiple items off the menu as equally good in whatever slot. I assume "any SI unit" means you don't care if we use m or km, and don't care if we use exponential notation or metric prefixes or long numerals or words. -- Beland (talk) 20:06, 25 July 2024 (UTC)
Yes, that is a correct interpretation. Dondervogel 2 (talk) 20:17, 25 July 2024 (UTC)
While I see the ideas behind Version 2, I think it's too complicated. We can't expect everyone to express separate preferences for compact and expanded format, and nobody should have to think about which prefixes for light-years they prefer. I'd keep it simpler, more in line with version 1: You have four possible units (ly, pc, km/scientific, m with prefix) – pick the two you prefer. ~~Maybe~~ Preferably ask for first and second unit too. My choices, similar to Dondervogel 2: ly or pc as first, km/scientific as second. Gawaon (talk) 20:08, 25 July 2024 (UTC)
I'd also argue for this. More complex options would probably prolong discussion and make things messier than they need to be. This discussion here is already quite protracted. ArkHyena (talk) 20:13, 25 July 2024 (UTC)
OK, so to clarify:
We're limiting this RFC to the compact format intended for infoboxes and tables, and after we get a clear answer on that discuss what to do about prose?

Are we pre-selecting a notation for extremely long distances for ly and pc? According to parsec, Gpc, Mpc, and kpc are standard. Despite the one-editor objection above, Gly, Mly, and kly seem to be used and understood, and seem a lot more compact than 93,000,000 ly (especially if there's an error margin) and more comprehensible and less cluttery than exponential notation.

-- Beland (talk) 22:10, 25 July 2024 (UTC)
We can probably survey for infoboxes and prose simultaneously, especially since I'd figure someone would bring up prose conventions at some point if it is not included in the first place—we'd just have to partition the survey as aforementioned to hopefully keep things smooth. And yes, Gpc, Mpc, kpc; and Gly, Mly, and kly seem to be well-established standards in relevant articles. ArkHyena (talk) 22:35, 25 July 2024 (UTC)
Should we then assume the expanded form (prose first or infrequent mention) would use unit names instead of symbols?

Should we also assume we're not using scientific notation for the expanded form and we'll use the words for multipliers greater than "thousand"? For example, "34.5 million light years (326 billion trillion kilometers)" if those units win the not-vote? ("Sextillion" isn't even in all dictionaries listed by Names of large numbers; when English Wikipedia uses it, it tends to be accompanied by exponential notation or other -illion words to explain what it means.) -- Beland (talk) 02:49, 26 July 2024 (UTC)
No, of course not, with distances like this, scientific notation will have to be used for kilometres in any case. Stuff like "billion trillion" is impractical to write and confusing to read. (And probably also confusing to write – indeed I think it should have been "billion billion" or "million trillion" (10¹⁸).) Gawaon (talk) 05:35, 26 July 2024 (UTC)

Also, it's common to abbreviate converted units in brackets also in prose, and I would assume that for our survey too. So the above example could be written as 34.5 megalight-years (3.26×10²⁰ km) – that's how {{convert}} does it. Though actually "million light-years" is probably better than "megalight-years" in prose. While I agree with that, I don't think such details should be part of this RfC, that would just be a needless overcomplication. Gawaon (talk) 05:58, 26 July 2024 (UTC)
OK, I've integrated all your suggestions into Version 3, above, which does feel a lot less overwhelming and easier to answer. I've tried to leave no ambiguity in the examples and use only formats with the strongest support, in case they are later taken as prescriptive (which they kind of will be if no one complains about them), and so no one can complain "if I'd known that's how we'd be writing this, I'd have voted differently". -- Beland (talk) 16:13, 26 July 2024 (UTC)
Yeah, that version looks fine to me. Gawaon (talk) 16:18, 26 July 2024 (UTC)

Yes, I agree it's reasonable to survey for infoboxes and prose together. People who have different preferences of units for one vs. the other should simply express that as part of their vote – I for one don't. But keep it one survey, with the option to express separate preferences for both in case they differ – nobody should be forced to vote twice, and certainly not in different sections. Stuff like Gpc and Mly sounds reasonable too, so we can used it in examples, but it's not what the RfC is about. Gawaon (talk) 05:34, 26 July 2024 (UTC)

Version 3 reads good to me! Gawaon (talk) 16:12, 26 July 2024 (UTC)
Agree here, version 3 looks good to go. ArkHyena (talk) 21:36, 26 July 2024 (UTC)
I just noticed that astronomical unit is absent. Is this a deliberate omission? Dondervogel 2 (talk) 16:23, 26 July 2024 (UTC)
Yes. Based on comments by Modest Genius and general practice I see observed in articles and the popular media, AU are used for distances inside star systems, but not the much larger distances between star systems. One light-year is about 63,240 AU, so even for relatively short interstellar distances, the numerical quantities are getting into the range where we'd normally start considering applying metric prefixes or exponential notation. 1 AU is the size of the Earth's orbit, so it makes sense to use these units for easy, intuitive comparisons of planetary orbits, and not for measurements on vastly different scales. I think it's unlikely that even if offered the choice, the wisdom of the crowd will favor AU, but that said, if anyone has strong feelings and wants to nominate AU to be included, I'm happy to add them. -- Beland (talk) 17:02, 26 July 2024 (UTC)
That's very reasonable. No need to add them on my behalf. I just wanted to check it was not an oversight. I also approve of the Version 3 wording. Thanks to those who have invested their time in the multiple iterations. Dondervogel 2 (talk) 20:27, 26 July 2024 (UTC)
Woo! If no one has any further suggestions or objections, I'll start the RFC with the version 3 text in the next 24-48 hours. -- Beland (talk) 20:33, 26 July 2024 (UTC)

Primary units and flipping

May I suggest that the units shown first should always be those quoted in the source document. The reason is that this is less likely to be distorted by rounding errors, and is likely to be more accurate than any alternative, converted figure. If "flipping" is allowed, then the user is left in doubt as to which of the two (or more) figures is more accurate, and in many cases also as to the precision of each figure. This means that some information is lost. Ehrenkater (talk) 15:17, 30 July 2024 (UTC)

Your rounding-errors argument makes no sense, since Convert will be working from the source's unit whether the display is flipped or not. The "user left in doubt" argument has at least some merit, but I believe it's completely outweighed by the fact that we'd be presenting values from different s sources with different unit orders, which will appear random to the reader. Johnuniq may have useful insight on this. E Eng 16:50, 30 July 2024 (UTC)

I prefer using the unit used in the source as the first in the Convert template, but usually flip to put the metric output first. Care must be taken to minimize rounding errors whether the outputs are flipped or not. Donald Albury 17:01, 30 July 2024 (UTC)

{{Convert}} is quite good with keeping the approximate precision of the source, and I agree that it's better to use flip as needed to get a consistent output. Consistency requirements within the same article suggest that the same unit should always come first (if possible), otherwise readers could get confused. Gawaon (talk) 17:06, 30 July 2024 (UTC)

Yes, and editors might use one source rather than another so that their preferred system of units comes first (see this talk-page's archives, too often). NebY (talk) 17:35, 30 July 2024 (UTC)

This is addressed in the Wikipedia:Manual of Style/Dates and numbers/Units of measurement/Unit choice and order. Shortcut MOS:UNIT. Basically this states that with the exception of the USA and the UK, the primary unit will be SI. Note that metric and SI are not the same thing. Sources can be cherry picked, the official government or company reference is a better choice. Magazines or newspapers generally round articles to their preferred unit. Avi8tor (talk) 19:44, 30 July 2024 (UTC)

Oh, I know MOS:UNIT says that and that sources can be cherry-picked - that's exactly my point and I've got the t-shirt. However, an official government or company release will not always be a better source, per WP:PRIMARY. NebY (talk) 19:53, 30 July 2024 (UTC)

Is there an example where distortion from rounding errors has occurred? Johnuniq (talk) 23:57, 30 July 2024 (UTC)

I commonly see in Wikipedia a distance of about 100 yards (91 m) when it's an estimation not a measurement, far to accurate in metres for "about or approximately." I have a copy somewhere of an article on a roman building excavation from 3 different newspaper sources all with different dimensions in feet only. Finding it on my computer may take a while, it's been a few years. Another example is engine power in motor vehicles, which since ~1980 in the EU has required it be stated in kilowatts. This hasn't stopped people from using PS, CV or HP because it's from their source. The best source is the owners manual, most available online. Avi8tor (talk) 04:59, 31 July 2024 (UTC)

Thanks but I meant an example of an article where someone had used {{convert|...|order=flip}} and where the result was distorted. It sounded as if the OP might have encountered the issue. Johnuniq (talk) 05:27, 31 July 2024 (UTC)

Flip was not involved. What I was thinking of was this, where {{Convert}} had a round number (700 km2) as input, and sigfig set to 1, which caused the output to round to 300 sqmi. This caused the sqmi output to be larger than the output from a conversion of 703 km2 to 271 sqmi. This was a list ranked by size, and it would have ended up with an entry showing as smaller than another entry when nmeasured in km2, and larger than that entry when measured in sqmi, if I had not changed the sigfig. Pay attention to the sigfig setting. Donald Albury 16:48, 31 July 2024 (UTC)

Interesting case, but I'd tend to leave out that parameter and let {{Convert}} do the right thing. Most of the time it seems to do a good job (700 km² (270 sq mi) looks reasonable too). Gawaon (talk) 17:03, 31 July 2024 (UTC)

'sigfig' has its uses. As with everything else in editing Wikipedia, one should inspect the output of any use of the convert template. Donald Albury 18:56, 31 July 2024 (UTC)

I suspect that you have something like this: a reference of 6 miles and an article that uses SI first. And that you "flip" by hand to get 10 km to make the SI appear first like {{convert|10|km/h|mph|0}} to display as 10 kilometres per hour (6 mph).
The answer (assuming I have constructed the right strawman) is to not flip by hand but to tell {{convert}} to swap the display order. Hence, you do {{convert|6|miles|km|0|order=flip}} to display as 10 kilometres (6 miles). This always uses the reference value in the wiki mark-up, displays SI first and does not do a double conversion. Stepho talk 07:56, 31 July 2024 (UTC)

If the reader sees 10 kilometres (6 mi) he or she will most likely assume that the accurate distance is somewhere between 9.5 km and 10.5 km (or possibly the 10 km could be only one sig. fig., there is no way of telling). However in reality the length is probably somewhere between 5.5 miles and 6.5 miles (or about 8.9 km to 10.5 km) so some information has been lost in the flipping. Ehrenkater (talk) 07:25, 2 August 2024 (UTC)

Few readers will care whether the exact length is 9.2 or 9.6 km and those that do will do better by either looking it up in the provided reference (where they'll find the original unit) or looking it up in some kind of primary reference collection that presents all distances in a uniform way and according to a uniform standard of reliability. Face it, a tertiary source like Wikipedia that gathers information out of all kinds of (hopefully reliable) sources is not the place to go if you're interesting in absolute precision. Gawaon (talk) 08:37, 2 August 2024 (UTC)

Ammunition calibre/length naming conventions

See discussion at WT:WikiProject Military history#Space before unit symbol. I had moved 14.5×114mm to 14.5×114 mm; another user pointed out it should be 14.5 × 114 mm; then I noticed it should be 14.5 mm × 114 mm per MOS:UNITSYMBOLS and said I don't want to go there. Can we consider revising the guidelines to allow dropping the unit symbol in such cases instead of repeating it? There are about 20 cartridge sizes with similar article title question; maybe more. Dicklyon (talk) 22:43, 8 August 2024 (UTC)

Hmm. In that article, "14.5x114mm" seems to be used as much as a proper noun as a pair of dimensions, in which case it might have any form (cf 2x4) and, like Nine Inch Nails, not require an exception here. NebY (talk) 23:05, 8 August 2024 (UTC)

Well, it's pretty clearly a descriptive name, not a proper name, and it appears various ways in sources, including with the mm twice in one source I found. So I'd say it's pretty clearly subject to editorial styling, by us and others, and it would be good to have an easy way to fit it into our style rules without using that "rarest" version. Dicklyon (talk) 00:14, 9 August 2024 (UTC)

It is a proper name, not a descriptive one. Although ammunition calibres may look like measurements and in some cases actually are, they often are not. This arises from the common practice of changing the name when the ammunition is incompatible rather than its actual size. That does not mean that it is not subject to our style rules, but do not try to use conversion templates. Hawkeye7 (discuss) 03:37, 9 August 2024 (UTC)

Having a space before the "mm" looks fine to me, since that's how metric units are officially written. Otherwise I agree we don't have to follow the intricacies of our style rules in all details, since as others have noted, it's a name, not really a measurement. So I'd leave the article name as it's now. Gawaon (talk) 06:09, 9 August 2024 (UTC)

My gut feeling is that this is the name of the ammunition, and was therefore probably OK as it was before the move (if it's a name there's no need for the space, and no need to repeat the unit symbol): '14.5×114mm' seems fine. If I'm wrong and this is a description of the dimensions, the space is needed and the unit symbol should appear twice, but I am not saying we should use '14.5 mm × 114 mm', because that implies a rectangular shape (and I kinda doubt we are talking about rectangular ammunition). If one of the dimensions is a diameter, a meaningful description would need to convey that, with a Φ symbol or similar.

My advice: keep things simple by treating it as a name. Dondervogel 2 (talk) 06:38, 9 August 2024 (UTC)

There are names and there are proper names. The wide variation in styling in sources, and the structure of it, suggest that it's a descriptive name, subject to editorial styling. Even at the milhist discussion the idea that it's a proper name didn't come up; go there if you want, since this discussion is about how our styling guidelines apply to treating it as a descriptive name. Dicklyon (talk) 15:59, 9 August 2024 (UTC)

This discussion is about whether our styling guides apply to names. MOS:UNITS applies to the names of units, but why should it apply to the names of anything else? I notice no enthusiasm at WT:WikiProject Military history#Space before unit symbol for being governed or guided by MOS:UNITS in this regard, or much concern about the matter at all. NebY (talk) 16:37, 9 August 2024 (UTC)

If we accept that it's a name, how would you style it, given that sources are all over the map on it? Dicklyon (talk) 22:38, 9 August 2024 (UTC)

I don't know that I've ever written about such ammunition and I may never, so I'm happy to leave it to the people who do have an interest in it. Indeed, if the sources are all over the map on it, it might not even be possible to find an acceptable and universally applicable norm, and there might be very little to be gained and something to be lost from seeking or imposing uniformity. NebY (talk) 22:35, 10 August 2024 (UTC)

I agree. I suppose what people mean (and I agree with that too) is that, since we're talking about a name rather than a number, MOS:UNITNAMES doesn't really apply. Though interestingly, MOS:UNITNAMES itself says: "The unspaced letter x may be used in common terms such as 4x4." That might be applicable to this case too. Gawaon (talk) 16:39, 9 August 2024 (UTC)

And notably, the linked article actually uses the spelling 4×4 – using × instead of the letter x, but without surrounding spaces. Gawaon (talk) 16:42, 9 August 2024 (UTC)

They appear to be names (which at least in the US are approved by the appropriate trade organisation - Sporting Arms and Ammunition Manufacturers' Institute) - see [12].Nigel Ish (talk) 08:57, 11 August 2024 (UTC)

Also note that while some ammunition names/designations appear to be dimensions that isn't necessarily the case - for example 357 Magnum and .38 Special both fire bullets of the same diameter, just the first has a longer cartridge and is much more powerful.Nigel Ish (talk) 09:11, 11 August 2024 (UTC)

I've infomed the firearms wikiproject.Wikipedia_talk:WikiProject_Firearms#Possibly_relevant_discussion_at_Manual_of_Style/Dates_and_numbers.Nigel Ish (talk) 09:23, 11 August 2024 (UTC)

Thanks! I hadn't noticed that one. Dicklyon (talk) 22:42, 11 August 2024 (UTC)

I've moved a couple: 12.7 × 108 mm and 14.5 × 114 mm. If anyone objects, say so or revert, and I'll start a multi-RM discussion. Dicklyon (talk) 22:42, 11 August 2024 (UTC)

Use of metric prefixes

As someone with high functioning autism I find it all nice, consistent and straightforward to use the whole range of metric prefixes (see article on those) at every opportunity (even instead of non-SI units even specialists tend to use), this to me (forgive me for any slight inaccuracies here these are to rounded figures and are off the top of my head ), the mass of an electron is 9.109 qg, the mass of a proton is 1.69 yg the electronic charge is 160 zC, the the dialect of a proton is about 1 fm, the depth of the world’s planned deepest swimming pool would be 5 dam, the height of the Eiffel Tower is 3.24 hm, Everest is 8.863 km high, the earth has a circumference of 40 Mm and a surface area of 510 Mm2, the volume of water in the Pacific Ocean is about 1 Mm3, the distance to the Moon is 384 Mm, the distance to the Sun is 150 Gm, the distance from the Sun to Saturn is 1.4 Tm, the distance to Alpha Centauri is 40 Pm, the distance to Betelgeuse is roughly 3 Em, the diameter of the Milky Way is 1 Zm with Andromeda 21 Zm away, the diameter of the Observable Universe is a Comoving 880 Ym, the mass of the Earth is 5.98 Rg and the mass of Jupiter is about 2 Qg. To me, it would be much more consistent and straightforward if all Wikipedia articles used the full range of metric prefixes to get people using them more and thus making more sense to me. Perhaps that change could be made, with people being directed to the metric prefixes page as needed to help them understand the wider range of prefixes. From the age of 12 I started to use the full range of prefixes them known to me in my schoolwork, and at virtual astronomy society I tend to butt in with the distance or mass expressed that way instead of earth masses or light years, for example. Avenues2009 (talk) 09:13, 21 July 2024 (UTC)

While I'm in favour of primarily using SI units whenever reasonable, we chiefly use the units that are most common in any given area, so general custom needs to change first before we follow suite. Hence we'll continue to use units like solar mass and astronomical unit in astronomy, nautical miles and knots in marine navigation (which fit the Earth's coordinate system better than SI units), and even feet for aviation. Also I'm pretty sure that years and centuries will remain more popular for expressing longer periods of time than mega- and gigaseconds, charming as the latter might theoretically be. Gawaon (talk) 09:44, 21 July 2024 (UTC)

Could both then be provided (including use of exotic prefixes in case of one) so not only is everybody else satisfied, so am I. Perhaps this could be done by always providing the SI with the exotic prefix in brackets (you can tell I am British here). Even if SI is already used but with a common prefix, perhaps the more exotic prefix could be provided in brackets. That would again satisfy all round. Avenues2009 (talk) 10:03, 21 July 2024 (UTC)

Template:Convert exists and can be used for such purposes. However, in less obvious cases or if you are reverted, it might be best to open a discussion on the talk page of the article in question. Gawaon (talk) 10:28, 21 July 2024 (UTC)

How does one use that to do two different conversions at the same time - eg thousands of kilometres to both miles and megametres, or astronomical units to both millions of kilometres and gigametres? Avenues2009 (talk) 11:24, 21 July 2024 (UTC)

One conversion should be enough, and units like mega- or gigametres that don't see any real world usage shouldn't be used at all. Gawaon (talk) 11:29, 21 July 2024 (UTC)

But that’s the whole point of me having started this discussion. With my high functioning autism, to me they should be used everywhere because that means everything is all straightforward and consistent. That’s why I wanted to be able to do two conversions at the same time, to bring them into use as well as what others prefer. Avenues2009 (talk) 11:57, 21 July 2024 (UTC)

Your high functioning autism doesn't mean the world will magically take the shape you would like it to take. Wikipedia is consensus-driving, and there is no consensus for the use of exotic SI combinations such as gigametres or megaseconds, even though they are theoretically valid. Gawaon (talk) 12:06, 21 July 2024 (UTC)

And it is much easier to say a measurement when using all the prefixes not just the common ones. Avenues2009 (talk) 11:58, 21 July 2024 (UTC)

@Avenues2009 Whats wrong with being autistic and not ranking it with "high functioning"? I'm autistic but I never say what functioning I might be. Anthony2106 (talk) 10:53, 15 October 2024 (UTC)

I echo the other concerns mentioned in other replies. I'll add that from the time the metric system was created about 7 Gs ago until the introduction of the International System of Units (SI) about 2 Gs ago a variety of ad hoc units were added, such as mmHg. Also, some of the original prefixes were found to be inconvenient. So SI recommends that hecto-, deka-, deci-, and centi- not be used, and only coherent units be used. However, the prefixes for multiplication or division by 10 and 100 are still used in entrenched cases, such as centimeter or decibel. Jc3s5h (talk) 13:22, 21 July 2024 (UTC)

Don’t you mean 7 Gs and 2 Gs? Avenues2009 (talk) 13:32, 21 July 2024 (UTC)

You're right, I fixed it.

It is not Wikipedia's job to try to promote metric prefixes in contexts where they are not used in the wider world, even if some individuals do use them in those circumstances. Most scientists in many fields - including, since you raise it, astronomy - don't use them - particularly the more extreme ones - because they are obscure and serve to confuse rather than enlighten.

I'd also note that even the largest metric prefixes aren't large enough for some astronomical data. I note that you fail to mention the mass of the sun, which is around 2 (non-existent-prefix)-grams. And there's plenty of of masses you might want to express that are many orders of magnitude larger than the mass of the sun. Kahastok talk 15:20, 21 July 2024 (UTC)

Perhaps a parallel example might be useful. I recently learnt a major reason why Americans keep rejecting the metric system. A major benefit of metric is the use of prefixes makes it trivial to convert from mm, to m, to km, and so-on. Except Americans are so used to the imperial (customary) system making it so hard to convert between inches, feet, yards and miles that they simple learn to not convert between units. So one of metric's major advantages is simply a non-issue to them.

The parallel here is that people use solar masses, AU, light-year, etc and just never convert them to other units. Only people writing software for things like interplanetary probes would ever do such conversions to kg, m, etc and they don't need Wikipedia for this info. So converting them to metric is not useful and the clutter it causes makes articles harder to read. Stepho talk 03:18, 22 July 2024 (UTC)

For me, articles would not be too crowded with such conversions thrown in. To me, they would be quite useful, as well as educational for all those who live between 5 and 12 Mm away from me in the US. Avenues2009 (talk) 06:47, 22 July 2024 (UTC)

The larger figure being included to encompass Hawaii by the way. Avenues2009 (talk) 06:50, 22 July 2024 (UTC)

Do you see what I mean there? I live in the UK, hence the distance I gave. Avenues2009 (talk) 22:30, 22 July 2024 (UTC)

I don't. Gawaon (talk) 05:54, 23 July 2024 (UTC)

Therefore such unit conversions would be quite useful and not make articles too crowded, because then you might. It would help Americans understand how much more useful the metric system would be for them. Avenues2009 (talk) 06:55, 23 July 2024 (UTC)

Nobody argues against the usefulness of commonly used metric units. However, Mm (as opposed to mm) is not one of them. Gawaon (talk) 07:05, 23 July 2024 (UTC)

Er, I'm American, and the ease of converting metric units is refreshing compared to trying to remember how many ounces are in a pound or a gallon, and I think makes metric quite attractive. We have to convert between customary units (we don't use imperial units since that system came after US independence) frequently, and to do that I either ask a smart speaker or look it up online if I can't remember the conversion factor. Generally, I think Americans find the metric system difficult to learn simply because they (outside of STEM fields and certain industries) don't use it every day and have no intuitive sense of what various quantities (like 100 km or 10 degrees C) mean. I think trying to add more prefixes into common use like gigameters or whatnot, would just mean more to memorize about the metric system, and thus make it slightly harder to learn, not easier. -- Beland (talk) 07:05, 23 July 2024 (UTC)

It doesn’t take much to memorise 24 prefixes. Avenues2009 (talk) 07:38, 23 July 2024 (UTC)

That's why I say "slightly harder" and not "a lot harder". I'm an American who does have a feel for what a kilometer is, and if you start speaking in megameters, you'll just make me do extra mental work to convert back to thousands of kilometers. If you start speaking in megaseconds, I and my European friends are probably just going to stop listening, because it's too much work to figure out what that means in years, which is the conventional and intuitive unit for long time. I'm an enthusiastic promoter of the metric system and use it whenever feasible, but anything above "tera" or below "milli" I'd have to look up.

I think a much better way to get Americans to learn the metric system (and one which already has broad consensus) is to make sure that every time a US unit is given on Wikipedia, there's a metric conversion right there. Since Wikipedia is consulted so frequently, I expect this would increase American exposure to the metric system significantly, since it rarely comes up in the news or in everyday life (unless you work in STEM or a few other narrow areas). Eventually I hope people would generate an intuition for metric units by sheer exposure.

This is currently required by MOS:CONVERSIONS, but there are hundreds of thousands of instances violating the guideline. I am actually working on adding conversions in my spare time, using moss to scan database dumps and JWB to quickly add in {{convert}}. I have tens of thousands of articles in a queue to be fixed for feet and inches alone, if you'd be interested in helping out. -- Beland (talk) 08:07, 23 July 2024 (UTC)

I don't think those conversions really do the job you think they do. I (and presumably many other Americans) simply learned to figure out which measurement to skip in any particular work, the one before the parentheses or the one inside them. They don't impinge on my consciousness anymore than a footnote number does. --User:Khajidha (talk) (contributions) 14:38, 9 September 2024 (UTC)

Sure, some people will gain more than others from exposure, and different media have different levels of effectiveness. Children, for example, who are continually exposed to the metric system might find it useful in enough contexts to never learn to gloss over it. I've noticed some American TV broadcasts giving temperatures in both Fahrenheit and Celsius, which is a bit jarring in contexts like that where Celsius is never mentioned. It's more difficult to unhear that than to have your eyes skip over a parenthetical. -- Beland (talk) 17:16, 9 September 2024 (UTC)

If you read the article on metric prefixes, there is a hint that at some stage in the future, double prefixes may return, with the restriction that the last one be quecto or quetta, but that has not happened her. That problem would be solved if they did return. Avenues2009 (talk) 06:23, 22 July 2024 (UTC)

So they can’t be used before that time if it ever happens. Avenues2009 (talk) 06:24, 22 July 2024 (UTC)

How is it more convenient to keep swapping prefixes instead of just using a single unit with scientific notation if needed? I'd much rather compare 0.04 km with 2000 km than compare 40 m with 2 Mm. Double sharp (talk) 09:17, 23 July 2024 (UTC)

Well I find it more convenient, it’s easier to say the measurement for a start if the prefixes are used. And instead of saying 40 m, you’d say 4 dam. Avenues2009 (talk) 10:03, 23 July 2024 (UTC)

Car power is expressed in 3 different units in Wikipedia articles, kW, hp and PS, so having 3 different units for astronomical distance could work. Some people do use these prefixes, look at the computer world, Gigabyte and PB are very common. When people see this it might open their mind to look into this unit and learn something, which after all is the reason for Wikipedia. Avi8tor (talk) 15:36, 23 July 2024 (UTC)

What a good idea. It would be great if that was implemented not only in astronomy but other fields as well. Avenues2009 (talk) 16:41, 23 July 2024 (UTC)

Different countries have different definitions of horsepower, including the German PS. I think the general trend is that kW is replacing horsepower in international commerce (and using kW as primary is now mandatory in the EU). It doesn't seem useful to encourage anyone to learn about horsepower or start using it when they otherwise wouldn't.

If you meant to reply to the question about light-years, this is the wrong section. -- Beland (talk) 17:02, 23 July 2024 (UTC)

Oh, when you say "3 different units for astronomical distance", you mean e.g. AU, km, and Gm or something? Having two meter-based conversions would seem to me to be adding clutter because a.) those conversions are easy for readers to do just by moving the decimal place, and b.) Gm is virtually unused, and thus not useful for conveying information about the subject of the article. The only reason to have it there would be to teach readers about obscure units in the metric system, which is not the point of Wikipedia articles except for Metric system and Metric prefix and friends. -- Beland (talk) 17:09, 23 July 2024 (UTC)

Then let’s have two metre-based conversions then, for that very purpose of teaching readers those obscure units. And let’s do it for distances beyond the solar system as well. Avenues2009 (talk) 17:13, 23 July 2024 (UTC)

Wikipedia is not a textbook. Teaching is not our primary task, and we don't have a right to decide who should be taught what. Gawaon (talk) 17:18, 23 July 2024 (UTC)

Yes, and we convert to alternative units to communicate quantities to people accustomed to this or that set of units, not to train people in the use of an unfamiliar one. NebY (talk) 17:36, 23 July 2024 (UTC)

But the more the unfamiliar ones were taught, the more they might catch on and become familiar. Avenues2009 (talk) 18:24, 23 July 2024 (UTC)

As WP:RIGHTGREATWRONGS says, Wikipedia is intentionally "behind the curve"; I think it would happily adopt such a change if it had already substantially caught on, but does not itself want to lead that type of movement. Sorry that's unsatisfying, given that I'm sure using the obscure units makes you and the original designers of the system happier than watching people use the metric system as they actually do. 8) -- Beland (talk) 19:01, 23 July 2024 (UTC)

I was thinking more AU or light years, miles and Gm or Pm for the 3 units. I've found that in general citizens of different countries use what they are fed, miles in the UK and USA and km elsewhere. The same with every other unit. The British empire used stones for weight, now only the UK used stones. It appears most younger people outside the UK have never heard of stones even though their mother tongue is English. Avi8tor (talk) 19:36, 23 July 2024 (UTC)

Currently, it's not required to convert into miles for STEM articles. In many cases we don't, and in some cases we're actively removing them. -- Beland (talk) 19:57, 23 July 2024 (UTC)

Well for astronomy you could instead convert into Mm,Gm, Tm, Pm, Em, Zm or Ym as the case may be, or for the Comoving circumference of the observable universe at least, Rm. That would make a lot more sense than miles. Avenues2009 (talk) 20:25, 23 July 2024 (UTC)

And the same with mass. It would make sense to have both kilograms, and the relevant prefix that would apply to a given value. Avenues2009 (talk) 21:34, 23 July 2024 (UTC)

And for large objects like stars, galaxies etc the second figure would be the number of Qg until such time as double prefixes are allowed again. Avenues2009 (talk) 21:40, 23 July 2024 (UTC)

Of the distance units mentioned, the units people actually use are AU/light years and kilometers. Ym might make more sense to you, but they don't make sense to hardly anyone else, and Wikipedia's goal is to communicate to as broad an audience as possible. -- Beland (talk) 22:58, 23 July 2024 (UTC)

Hence the suggestion of converting to both km and a more appropriate prefix so things make sense to me as well as to others. Avenues2009 (talk) 06:09, 24 July 2024 (UTC)

When I say people use kilometers, I mean people use kilometers, not Ym. How many people do you think actually use Ym or would understand them on sight? -- Beland (talk) 15:41, 24 July 2024 (UTC)

I’ve met one or two actually. Avenues2009 (talk) 19:20, 24 July 2024 (UTC)

And they even understand what it stands for - yottametres. Avenues2009 (talk) 19:21, 24 July 2024 (UTC)

That's not really enough information to get a handle on the overall ratio of English speakers. How many people have you met who would not understand Ym? What is your sampling bias compared to English Wikipedia readership? -- Beland (talk) 22:06, 24 July 2024 (UTC)

The sampling size is the groups I belong to, including astronomy society, and all my friends. But it really does make sense to use the prefix just below a value. It makes measurements much easier to write or to say. Avenues2009 (talk) 22:14, 24 July 2024 (UTC)

My astronomy society do not seem to understand Mm to Rm (megametres to ronnametres) so if these changes were implemented on Wikipedia that I am here asking for, we’d teach them. They’re technical and brainy enough, there are several of my fellow PhD holders among them, as well as a few teachers, so it would be very easy for them to learn and adopt any missing prefixes out of the 24 available. Avenues2009 (talk) 22:17, 24 July 2024 (UTC)

If even a specialty audience needs to be taught how to read the units, the vast majority of readers will certainly not know them on sight. We've already established it's a non-starter if readers don't already understand the units Wikipedia would be using across tens of thousands of articles. -- Beland (talk) 23:15, 24 July 2024 (UTC)

The goal is to communicate clearly with as wide a readership as possible. Do you believe that there are people who understand what a Ym is but don't understand what a km is? What then is the advantage of adding measurements in Ym (and the other obscure units you've proposed), other than satisfying your own personal sense of consistency? CodeTalker (talk) 22:12, 24 July 2024 (UTC)

It would satisfy my desire for consistency. Having the obscure unit included besides km (or kg) in a double conversion, would do that as well as be educational and informative that there are many other prefixes people can use as well. Avenues2009 (talk) 22:20, 24 July 2024 (UTC)

Although people can read the article on prefixes if they want to, they would be more likely to learn about them if they saw them in use, which such double conversions would enable. Avenues2009 (talk) 22:26, 24 July 2024 (UTC)

You're just repeating the same arguments you've already made and which have already been objected to. I could make the same objections again, but we're just going in circles, so it seems there's no point continuing this thread. -- Beland (talk) 23:18, 24 July 2024 (UTC)

The Manual of Style does ask for things to be in SI where possible and for unfamiliar units to be explained. So that is why I would like to see the full range of prefixes brought in using double conversions. Avenues2009 (talk) 07:55, 26 July 2024 (UTC)

I thought double conversions would help explain them. Anyway, that is my view. Avenues2009 (talk) 09:43, 26 July 2024 (UTC)

The MOS says that because unfamiliar units that must be used to explain the subject need to be explained. It's not asking to use unfamiliar units on purpose. Double conversions would add clutter which would make it slightly more difficult for readers to learn about the subject of articles. -- Beland (talk) 14:41, 26 July 2024 (UTC)

Ok. Avenues2009 (talk) 18:40, 26 July 2024 (UTC)

Ok, I run with that, although I still feel that if a metric prefix has been devised, one might as well use it because that is what it was devised for. Avenues2009 (talk) 08:49, 28 July 2024 (UTC)

No, some were devised merely for completeness, at a time when there was no foreseeable use for them. For example, it appears that while ronna (10^27) and quetta (10˄30) were added in anticipation of the need to express ever-larger quantities of data, ronto (10˄-27) and quecto (10˄-30) were added simply for symmetry with the other two [13] -- no one envisions anything (yet) they might actually be used for. E Eng 13:55, 1 August 2024 (UTC)

Using circa template only at first occurence

Is there a reason why the c. template should only be used at the first occurence in an article? To me, this rule seems weird, and it also just looks quite inconsistent. I can remember reading the guideline a long time ago, when it wasn't like that (I checked the version history and saw this has indeed not always been the case). I'm asking out of curiosity, because I can't think of any reason for it. Thanks in advance. Maxeto0910 (talk) 21:51, 14 July 2024 (UTC)

Because it brings up a tooltip to explain what it means. It's annoying to see that at every occurrence. (Honestly I think it's a little annoying to have it at all, but the one occurrence I can live with.) --Trovatore (talk) 21:54, 14 July 2024 (UTC)

The dotted underline? I understand that by comparison as I said below, but this may truly boil down to a matter of taste. Different strokes and all. Remsense诉 21:57, 14 July 2024 (UTC)

To be honest I don't really like the tooltip interface for Wikipedia at all. The little floating question mark does not seem to be that much used these days (it reminds me of — Encarta, I think? Something of that vintage anyway). I don't think Wikipedia should be proliferating UI elements, particularly ones that show up only occasionally.

And I don't really think "c." needs explanation. Give readers some credit.

That said, I can live with the one occurrence. --Trovatore (talk) 22:11, 14 July 2024 (UTC)

It's not a Wikipedia thing, it's an HTML thing. And I imagine it's distinctly less pleasant reading for those using screen readers to hear "see dot" each time. (One can disable the tooltip, but I still don't think it should be the guideline across the encyclopedia to do so.) Remsense诉 22:13, 14 July 2024 (UTC)

Ah, do they hear "circa" when the tooltip is used? Is that true for other tooltips as well? I wasn't aware of that. --Trovatore (talk) 22:17, 14 July 2024 (UTC)

Quite! See also the MDN doc for the <abbr>...</abbr> tag. Remsense诉 22:20, 14 July 2024 (UTC)

Also, not to say it's a replacement for this discussion, but since you dislike it, you could add

abbr { text-decoration: none; } to your common.css to hide them all forever. Remsense诉 22:53, 14 July 2024 (UTC)

It seems a reasonable rule, consistent with the MOS on overlinking and saving both readers and editors from a repeatedly cluttered experience. NebY (talk) 22:18, 14 July 2024 (UTC)

I also think this shouldn't be the guideline. I imagine the reason is that it's visually obtrusive à la one of the reasons against overlinking—but I simply don't think they're comparable, especially given accessibility reasons. Remsense诉 21:56, 14 July 2024 (UTC)

I agree, and I fact I wasn't aware that we are supposed to use it just once per article (or per section, maybe?). In my experience, it's most often used in captions, where it's quite reasonable to treat each caption as fairly independent of the rest of the article. I'd suggest writing something like "the use of the {{circa}} template is preferred over just c., at least for the first occurrence in a section or caption. At later occurrences, writing c. (followed by a non-breaking space) or using the {{circa}} template is preferred over ..." Gawaon (talk) 07:03, 15 July 2024 (UTC)

Or actually, because of the accessibility issue discussed above, the best course of action (and also a very simply one) is surely to recommend always using the template. Gawaon (talk) 07:08, 15 July 2024 (UTC)

I agree, if it makes the text more accessible for people using screen readers, that seems a good thing. Also, while many or most readers may not need an explanation of what c. means, the benefit of helping those who do need an explanation seems to outweigh any harm from using the template, especially as the text decoration can be hidden if particularly disliked. Mgp28 (talk) 09:37, 15 July 2024 (UTC)

I agree it's exceptionally annoying and should be deprecated in all circumstances. -- Necrothesp (talk) 13:48, 16 July 2024 (UTC)

Just a reminder that mobile users are unable to interact with tooltips at all. For me, {{circa}} yields c. No amount of peering directly at the character seems to activate the onHover action. Folly Mox (talk) 01:36, 4 August 2024 (UTC)

Does it do anything if you tap it? --Redrose64 🌹 (talk) 07:04, 4 August 2024 (UTC)

I agree, we don't need the tooltip at all. It's no more needed that a tooltip for vs., a.m., p.m., etc., or any other abbreviation of a term that originally came from Latin but is now just a common English word. oknazevad (talk) 06:44, 6 September 2024 (UTC)

RFC for units of the longest distances

What units should be used for distances between star systems and galaxies? These are measured in light years (ly) in popular news and educational media; professional astronomers use parsecs (pc). Articles currently use a variety of units (some only ly and some ly converted to km) but most commonly use ly converted to pc in infoboxes (often automatically from technical data). If conversion to SI units (like kilometers) is not required in certain contexts, this would be added as an explicit exception to MOS:CONVERSIONS. The maximum distance in the observable universe is under 100 billion light-years, and interplanetary distances (inside a star system) are a fraction of a light-year and are measured in astronomical units (AU or au). 01:40, 28 July 2024 (UTC)

Two formats are needed: an expanded format for use in article prose (especially on first mention), and a compact format for infoboxes, tables, and prose where the expanded format would be excessively long. The "unless this would be excessive given the context" rule from MOS:CONVERSIONS will still apply when the units are used several times in prose. First use of light-year/ly, parsec/pc, and rare meter prefixes (e.g. zettameter) must be linked to their articles, per MOS:UNITS. The chosen formats need to accommodate simple cases and complex expressions of precision (examples below).

The choices nominated for inclusion are:

Light-year (ly) with SI prefixes (kly, Mly, Gly) and large number words (million, billion) in prose
- 34.6 ± 0.3 million light-years (ly) [first mention in prose]
- 34.6 ± 0.3 Mly [compact]
- 408–548+90
  −49 ly [compact]
Parsec (pc) with SI prefixes (kpc, Mpc, Gpc)
- 765 ± 2 kiloparsecs (kpc) [first mention in prose]
- 765 ± 2 kpc [compact]
- 125-168.1+27.5
  −14.9 pc [compact]
Kilometer (km) with scientific notation
- 3.27×10¹⁴ km [compact, secondary in prose]
- 3.273×10¹⁴ ± 2.8×10¹² km [compact, secondary prose]
- 68.1+7.5
  −4.1×10¹⁴ km [compact, secondary in prose]
- 3.27×10¹⁴ kilometres [primary expanded]
Meter with SI prefixes (Ym, Zm, Em, Pm, Tm)
- 68.1 zettameters (Zm) [first mention in prose]
- 68.1 Zm [compact]
- 68.1+7.5
  −4.1 Zm [compact]

You can of course advocate for as many or few options as you find appropriate, or assert multiple options are equally good, but previous discussion has assumed at most two units would be used because many editors find three to be excessive. Please specify your preferred order; "primary" units come first and other units are converted to (typically in parentheses in prose, sometimes on a new line or after semicolon in infoboxes).

01:40, 28 July 2024 (UTC)

Your preferred units

Please note your preferred units for both compact-in-infobox and expanded-in-prose if they are different.

Light-years only. If there's a second unit, strong preference for kilometers. Astronomy infoboxes are already number-heavy; adding conversions makes them even more overwheming and unapproachable to the general public, which is a chronic problem in popularizing science. Light-years give nice, easy-to-understand small numbers for which we don't need exponential notation, avoiding overloading brains and having people mentally label everything from planets to galaxies as "incomprehensibly far" and more or less equally distant. It's easy to remember Alpha Centauri is about 4 ly away and the Milky Way is ~100,000 ly across and calibrate intuition from there. The speed of interstellar spacecraft (of which there are none) are sensibly measured in fractions of c, not km/s, and not parsecs per year (!?). If there is going to be a secondary unit, I strongly prefer kilometers, for consistency with all other articles and smaller measurements in infoboxes. Parsecs are too close to light-years and are only useful to specialists, who can easily do the conversion if they need to. I'm less opposed to conversion to km in prose because it feels less overwhelming, especially if it's only done sparingly, and it gives a sense of just how big a light-year is compared to everyday life. That said, it's not wrong to expect people to develop an intuition of how big a light-year is on their own or by reading light-year if they are new to the concept. -- Beland (talk) 01:44, 28 July 2024 (UTC)
Parsecs or light years as primary, kilometres as secondary (converted) unit. I have no strong opinion regarding the use of pc or ly as primary unit, but figure that pc are to be more useful since they are preferred by specialists. I strongly favour the use of SI units with scientific notation as secondary unit, since it'll give normal (lay) readers a better sense of the dimensions involved – most people know what a kilometre is, and even those more accustomed to miles will know that they are of roughly the same scale. Using other SI prefixes such as zettametres would in theory comply even better with the SI, but few people know prefixes of such dimensions, so in practice it would be much less helpful than km with scientific notation. Gawaon (talk) 05:44, 28 July 2024 (UTC)
Light-years first, parsecs second. We need to use light-years because that's what our readers understand, and parsecs because that's what our sources use. km is useless, both for intuitive understanding (a gigantic exponent gives no intuition other than gigantic distance), and for calculations (as relevant speeds are given in fractions of c). Em, Zm, Ym are even worse, these SI prefixes are way too obscure. Tercer (talk) 08:17, 28 July 2024 (UTC)
Light-years only. Agree (mostly) with Beland. Lightyears give an understandable number for the general public such that distances to different stars can be compared (eg 4 light-years to Alpha Centauri vs 100,000 light-years for the width of the galaxy). km's at that scale are all are read as an equal "damn that's big!" and are totally unrelatable - the average reader simply does not think in terms of numbers that big. km clutters up the article with no payback. Parsecs are not known to the general public (professionals know how to convert and probably get their information from better sources than WP anyway). Stepho talk 08:47, 28 July 2024 (UTC)
Light-years first, whatever unit is the primary unit used in the source second. We should be making it easy for our readers to understand, and not trying to shoehorn the content into some "official" style that will be more or less meaningless to many readers. I do support converting the primary unit used in the source to light-years, flipping the output as needed. - Donald Albury 17:45, 28 July 2024 (UTC)
Light-years, because that's the unit used by Patrick Moore, one of the most prolific authors of popular astronomy books. If the source uses another unit, state that as well, using {{convert}} with |order=flip. For example, if the source says 123 parsecs, we would enter {{convert|123|pc|order=flip}} which emits 400 light-years (123 pc). --Redrose64 🌹 (talk) 18:08, 28 July 2024 (UTC)
Parsecs, or if necessary pc+ly (pc first) using {{convert}}, for consistency with the professional literature. We need Wikipedia to be usable as a professional resource, not merely a dumbed-down only-for-the-public childrens' encyclopedia. —David Eppstein (talk) 18:34, 28 July 2024 (UTC)
The guideline Wikipedia:Make technical articles understandable makes a useful distinction between what I would consider "dumbing down" - WP:OVERSIMPLIFY which says not to oversimplify or tell lies-to-children - and "writing one level down", which WP:ONEDOWN says is a good rule of thumb for technical subjects.

In finding a middle ground between the overly technical and the oversimplified, §Avoid overly technical language specifically advises: "If no precision is lost, use common terms instead of technical terms. Substitute technical terms with common terms where they are completely equivalent." Whether that advice should apply in this situation is a matter of opinion, but I think it's important to remember that "making accessible" and "dumbing down" are not always the same thing. -- Beland (talk) 15:54, 29 July 2024 (UTC)
Making accessible should also mean, making accessible for professionals to read and to edit. "The widest possible general audience" should include professionals, not just non-professionals. Gratuitously avoiding the preferred unit of professionals makes our articles less usable to and less editable by them, for no good reason. It sends the message that their participation is not welcome here, the opposite of what we want. —David Eppstein (talk) 01:49, 30 July 2024 (UTC)
The discussion in the previous thread has several examples of peer-reviewed astronomy papers that use light-years, even though it's not the majority, and the unit is well-known in the popular press, which professional astronomers are also exposed to. Light-years should be perfectly accessible to professional astronomers and those familiar with the peer-reviewed literature, and no doubt already occasionally use the conversion factor to compare figures from different sources.

I was also pondering whether or not it would be good to also have parsecs to attract more professionals to use Wikipedia articles for quick reference, and possibly fix things while they are here. This past week I went through and fixed the densities and surface gravities of a lot of exoplanets; a few seemed completely wrong because someone had confused g/cm³ with kg/m³ or missed undoing a logarithm or just pulled data from a contradictory source without leaving a citation. Those sorts of things I would expect a professional to occasionally spot.

I think it would be good to get actual data about whether or not this makes a certain community feel unwelcome, rather than go on the guesses of non-astronomers about other people's emotional reactions. Does not using US units in science articles make Americans feel unwelcome? This American certainly does not, so I'm a bit skeptical of this idea. I might feel differently if someone did it intentionally to spite Americans rather than for good reasons, like reducing clutter for a global audience and the fact that STEM fields tend to use metric and Americans are an inconvenient minority on the planet in this aspect. I took some astronomy and planetary science classes while I was an undergrad at MIT, but I'm definitely not a career astronomer. Is anyone else here a professional astronomer or know someone who is and is uninvolved in this discussion so far? -- Beland (talk) 03:29, 30 July 2024 (UTC)
(See Parejkoj's reply, below, for one answer.) -- Beland (talk) 18:34, 1 August 2024 (UTC)
Light-years as primary unit, as the most familiar and understandable way of expressing interstellar distances. Parsecs as secondary unit, as the unit most often used by professional astronomers. Sources always use one or both of light-years and parsecs. While I prefer the status quo of using both I would also be okay with only light-years; compact tables like the list of nearest stars should use only light-years. Using large numbers of kilometers is not supported by common usage, and it seems clear that this being more understandable than light-years is a minority position. SevenSpheres (talk) 18:38, 28 July 2024 (UTC)
Light-years as primary unit (and perhaps the only unit) as the mostly widely understood unit. I don't like the idea of using parsecs. The point of providing multiple units is to allow the reader to understand the number if they are unfamiliar with the primary unit. I can't imagine that there's anyone who knows what a parsec is but doesn't know what a light-year is. Parsecs are used only by professional astronomers, who certainly know what a light-year is and can easily convert between light-years and parsecs. Furthermore, it seems unlikely to me that a professional astronomer would be doing research using Wikipedia rather than more professional resources. Well-respected popular science magazines like Astronomy and Scientific American use light-years. Weak preference for km as a secondary unit if a secondary unit is necessary, although the huge numbers involved in the conversion to km will probably be hard to understand for a significant number of our readers. CodeTalker (talk) 19:05, 28 July 2024 (UTC)
Well, if edited with that attitude, it is unlikely that our astronomy articles will be usable by professional astronomers. But in other areas of science, Wikipedia is usable, useful, and used by professional researchers, not so much as a source for data but as a good starting point for literature reviews and starting material for understanding topics with which they may not already be familiar. —David Eppstein (talk) 20:02, 28 July 2024 (UTC)
I certainly know chemists who use Wikipedia to look up reference data on certain molecules sometimes, but when doing so occasionally spot errors. We generally don't convert those data to secondary units in chem infoboxes (though I do see some Fahrenheit). It seems the benefits of using a single set of units - which we're lucky enough to also be those used in industrial and academic chemistry - outweigh the convenience for Americans who might be thinking or calculating in US units. It seems a bit much to claim that using light-years and not parsecs would make Wikipedia articles unusable for astronomers; how hard is it to divide by 3.26? -- Beland (talk) 05:24, 29 July 2024 (UTC)
@CodeTalker: The "huge numbers involved in the conversion to km" are one reason why such a conversion is helpful. An astronomer does not need reminding of that vastness, and uses parsecs for convenience, but the mindboggling vastness of space is lost when we use correspondingly vast units. The mindbogglingly large numbers resulting from a conversion to km (or mi) is one way of conveying the vastness to a lay reader. Dondervogel 2 (talk) 19:12, 1 August 2024 (UTC)
My opinion is that "conveying vastness" should not be a goal. The goal should be writing in a way that helps the reader to understand, not to awe them with wonder. I think few readers who are not already mathematically inclined will take anything away from numbers like 10²⁰ km or 10²⁵ km, except that they're both "very big", without any understanding of what they really mean or the difference between them. CodeTalker (talk) 19:36, 1 August 2024 (UTC)
If it is not Wikipedia's goal to convey how far away the stars are, then I too see little point in converting to km (or Zm). There we can agree.

But in my view a good encylopaedia should strive to convey precisely that. It seems this is where we differ. Dondervogel 2 (talk) 20:10, 1 August 2024 (UTC)
Of course our goal is to convey how far away the stars are. I don't see how you can read my response to mean that we should not. But it should be done in a way that is understandable to readers, not to deliberately use inappropriate units so that we can impress the reader with big numbers. CodeTalker (talk) 20:16, 1 August 2024 (UTC)
Space is big. Really big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the street to the chemist, but that's just peanuts to space. Listen... – Douglas Adams, "Fit the Second", The Hitchhiker's Guide to the Galaxy.

The point is that we cannot conceive very large numbers, so there's no point in choosing one unit over another unless you are comparing one distance with another, in which case you can judge that this object is ten times as far away as that object, when measured using the same units. --Redrose64 🌹 (talk) 21:01, 1 August 2024 (UTC)

Your precise words were "conveying vastness" should not be a goal. I interpreted that as meaning Wikipedia should not try to convey the vastness of space. I see no other reasonable interpretation. If not that, what did you mean instead? Dondervogel 2 (talk) 22:35, 1 August 2024 (UTC)
Not to put words in anyone's mouth, but I think the idea is that light years give small numbers that can be readily compared to easily comprehend relative distance. Distances in light years convey the mathematical information about how far away the stars are, but do not convey a realistic sense of sheer vastness unless one already has an intuition for how vast a light-year is. As compared to kilometers, which can (for those who understand scientific notation and who stop to think for a moment) convey an intuitive sense of how far away stars are in absolute terms, for example by making it easy to see how long it would take to drive there at 100 km/h or how long it would take Voyager 2 to get there at 15 km/s. -- Beland (talk) 03:43, 2 August 2024 (UTC)
Yep. The distances need to be presented in light-years (or parsecs), to provide relative distances and in kilometres (or metres) to convey the vastness. Very well put. Dondervogel 2 (talk) 06:37, 2 August 2024 (UTC)

The main sticking point here seems to be over if it is within our purpose to do so (re: km conversion).

Personally, I would say it is not. ... for example by making it easy to see how long it would take to drive there at 100 km/h or how long it would take Voyager 2 to get there at 15 km/s. Including conversions solely for this purpose feels uncomfortably close to WP:INDISCRIMINATE to me. Unit conversions are included for reasons of practicality, not for conveying "vastness" or other arbitrary properties.

There are, of course, other arguments for include km conversions that others have laid out, but I feel that this specific line of reasoning is a weak one. ArkHyena (talk) 08:05, 2 August 2024 (UTC)
Conveying vastness essentially means providing a comparison with a familiar unit. Thus providing distances in, say, kilometres enables readers to compare the distance to a measure they use frequently, and providing them in a large unit such as light years enables readers to more easily compare the relative distance for different stars. isaacl (talk) 13:35, 2 August 2024 (UTC)
My stance that such a reason alone is not sufficient still stands. I fail to see how SI conversions would enable a reader to more easily compare the relative distance for different stars, because that is, in part, why we use lyr/pc in the first place. A star 50 lyr away being twice as distant as a star 25 lyr away is perfectly understandable to the reader. On the topic of vastness, we don't provide the masses of planets in kg just to convey to the reader how massive they are with impressively large numbers, we include them because
Kg are occasionally, if not frequently used by astronomers when dealing with the masses of celestial objects, including planetary ones

There are relevant attributes that rely on their masses being given in kg, such as planetary densities, planetary compositions, or the masses of a planet's internal layers

If we are to include SI conversions for lyr/pc, we ought to do so for similarly practical reasons. ArkHyena (talk) 19:50, 2 August 2024 (UTC)
My previous position was parsec or light-year as primary unit, converted to SI, but I now favour parsec as primary unit, converted to SI. I will explain the rationale behind the shift in a follow-up post, but my thoughts remain in a state of flux and the popularity of the light-year makes me consider the need for a 3-way conversion in some situations. I will be back. Dondervogel 2 (talk) 21:14, 28 July 2024 (UTC)
… and my considered preference is Parsec as primary unit, converted to an SI unit. In prose, convert also to light-years, thousands of light-years, millions of light-years, billions of light-years (avoiding the abbreviations 'ly', 'kly', 'Mly', 'Gly'), as appropriate.

My preferred SI unit would be Pm, Em, Zm or Ym, linked on first use to petametre, exametre, zettametre, yottametre. I can see the benefit of relating to the kilometre (km), so I would not object to that option, although I find the exponential notation cumbersome.

As mentioned in my previous post, I no longer favour the use of light-year as a primary unit. I was already uneasy about “megalight-year” and similar but was unsure why. When I dug a little deeper I discovered the IAU style manual, which lists SI units and non-SI units recognised for use in astronomy. The units recognised by the IAU are the metre (symbol m), the astronomical unit (symbol au = 0.149 60 Tm) and the parsec (symbol pc = 30.857 Pm). In other words, the IAU does not recognise the light-year for use in astronomy. And if the IAU does not recognise the unit, we should not use it, right? No, not quite. Many Wikipedia readers will know a light-year is the distance light travels in a year, and this familiarity makes it relevant, hence the proposed additional conversion (in prose) to light-years, but avoiding the abbreviations ly, Mly, etc., which I find unhelpful.

The conversion to SI provides a scale (whether the metre or kilometre) that all readers are familiar with and conveys the vastness of space in a way that parsec (or light-year) on their own do not achieve (Readers who understand the meaning of ‘light-year’ as the distance travelled by light in a year do not necessarily have a grasp of how fast light travels; only yesterday I was asked “what travels faster, light or sound?”)
Examples
- Sirius B is 2.670 pc (82.4 Pm; 8.71 light-years) from the Sun.
- The Whirlpool Galaxy is 7.220 Mpc (223 Zm; 23.5 million light-years) from the Sun and 23.58 kpc (0.728 Zm; 76,900 light-years) in diameter.
The use of 0.728 Zm in preference to 728 Em avoids an unnecessary conversion between Zm and Em in the 2nd example. The SI values could be replaced with exponential notation if that is preferred. I find it cumbersome but that is a personal preference. Dondervogel 2 (talk) 13:57, 29 July 2024 (UTC)
Finally someone who would agree with me in the discussion on prefixes I started. Avenues2009 (talk) 21:37, 30 July 2024 (UTC)
I can see the benefit of SI prefixes in astronomy and nuclear physics, because the prefixes obviate the need for cumbersome exponential notation. Where we differ is your statement it would be much more consistent and straightforward if all Wikipedia articles used the full range of metric prefixes, which differs from my position. In 99.9 % of our articles it is preferable to use a scale between "millionths of a millimetre" and "millions of kilometres", as appropriate. Dondervogel 2 (talk) 09:11, 31 July 2024 (UTC)
Light-years as primary unit, parsecs as secondary unit, as lyr are indisputably the primary unit used to convey interstellar distances or larger. I don't see why distances measured by lyr/pc should be converted as such distances are well into the region where scales conveyed by kilometers are, at best, impractical and unintuitive to most. This is evidenced by numerous science communication outlets—including NASA itself—excluding SI (or US customary) conversions for interstellar distances (some examples: [14] [15] [16] [17]). It is clear that the overwhelming majority of science communication, nevermind technical introductory sources such as astronomy textbooks, deems such conversions as largely unnecessary, and I fail to see why we should be any different. ArkHyena (talk) 02:52, 31 July 2024 (UTC)
None of the web pages you linked use parsecs, either. -- Beland (talk) 03:17, 31 July 2024 (UTC)
Yes, but this is balanced by the fact that academic sources overwhelmingly use pc over lyr. Popular sources use lyr, academia uses pc; per this, we should use both, with the less technical lyr being our primary unit. ArkHyena (talk) 03:19, 31 July 2024 (UTC)
Interestingly, our dab page lyr doesn't mention light-years. --Redrose64 🌹 (talk) 19:59, 31 July 2024 (UTC)
Should be fixed now, thanks for the heads up :) ArkHyena (talk) 20:04, 31 July 2024 (UTC)
Our article light-year also doesn't mention "lyr", a contraction which I had never come across until your post of 02:52, 31 July 2024 (UTC) - everybody else in this section, when abbreviating, has used "ly". I hope that "lyr" is not something that you made up. --Redrose64 🌹 (talk) 07:13, 1 August 2024 (UTC)
I suppose it's a mistake. Gawaon (talk) 07:33, 1 August 2024 (UTC)
Both "ly" and "lyr" are legitimate abbreviations of "light-year". I have seen "lyr" in reliable sources (e.g., Mutel et al 1981; Chen & Chen 2016). It should be mentioned in Light-year as a legitimate alternative to "ly". Dondervogel 2 (talk) 08:05, 1 August 2024 (UTC)
I have added "lyr", "klyr" and "Glyr" to Light-year, citing RS. Dondervogel 2 (talk) 08:17, 1 August 2024 (UTC)
Light years as primary, small preference for conversion to parsecs in extended prose. Professional astronomer here (there's about a half dozen that I know of that semi-regularly edit Wikipedia): parsec is really useful because the relationship between arcsec, au, and pc (and the conversion factor of 206,265) allows really easy conversion between measured angular sizes, proper motions, distances, etc. in one's head. But that's not something that most people will ever have to care about, so there's not a strong reason to use pc on Wikipedia, except that that is the value that most primary sources report. I like the suggestion above to use `order=flip` in the converter, since that helps make it clear where the value came from: we have a terrible problem of un- and poorly-sourced numbers in astronomy articles.
Metric prefixes for meter are right out: most astronomical scales are well beyond what any typical reader would be familiar with; I work computing, and still have to remind myself what the exponent for peta is. Prefixes above giga would be completely unfamiliar to most readers.
To the question of whether astronomers are, or should be, using Wikipedia as a data source: I mostly hope that they do not. We have our own curated sources for data values (e.g. NED, SIMBAD, or the SDSS value added catalogs), and it's almost always not as simple as just grabbing the "top" value from a catalog. This often happens on Wikipedia, and results in long arguments by non-experts about e.g. which star is biggest. I've tried at various points to get colleagues to edit wiki pages when they notice something incorrect without much success; you don't get tenure or grant funding editing wiki! We're not going to turn Wikipedia into a preferred source of numerical values without essentially re-creating the work that went into something like SIMBAD, and that took *significant* funding and buy-in from institutions. Trying to re-create that work without experts onboard is not worth our time. - Parejkoj (talk) 03:58, 31 July 2024 (UTC)
Light years as primary. I would include a conversion to parsecs (using order=flip if it helps). Light-years are widely recognised by the lay reader, which will be most of our audiences. Parsecs are more likely to be found in sources (so including them helps with verification) and will be needed if we aspire to have an audience of professionals. I would not strongly object to a third conversion to kilometres where space allows, but I would strongly object to the use of obscure metric prefixes that would not be readily understood even by professional astronomers or other professional scientists. Shoot, even names of large numbers are more understandable to more people (even if we restrict ourselves to professionals) than most of the larger metric prefixes. At least you can work out how big a quintillion is from its name. You can't do that with exa-, zetta- or yotta-. Kahastok talk 21:40, 2 August 2024 (UTC)
I feel it's worth adding something on the kilometres point. My view is that conversions from light years to kilometres are unnecessary in general. Such conversions are almost never found in other sources on the topic. And that's because systematically converting interstellar distance to kilometres is as useful as systematically converting the lengths of running races into light-years. In general, I believe that light-years are sufficiently well-known that, per my point below, most readers will understand them. However, I do not strongly object. I do see some small amount of value in helping readers quantify some of these very large distances in niche circumstances, and I don't see a huge harm in using them occasionally - in infoboxes but not in prose, for example. Of course, no such value arises from units using obscure SI prefixes to create things like exametres and zettametres, as these are less likely to be understood than the units they're supposed to be trying to explain. Kahastok talk 17:14, 3 August 2024 (UTC)
Lightyears first, with parsecs (second choice: parsecs + lightyears). Lightyears first, for our general readers. Parsecs second, for those more familar with astronomy at that scale, readers and editors both, and for the sake of our reputation. Not kilometres, for several reasons; my big two are that few have the skill of comparing values in exponent notation at a glance, without having to separately scale left and right portions, and that any comparison to terrestrial dimensions or speeds tells us only that each sidereal distance is vastly greater and would take inordinate time to cross at any ordinary travel speed, but nothing about this or that particular sidereal distance – or to put it another way, kilometre sidereal distances are good for the sort of fantasy math that we might try once or twice in a lifetime but not for regular use across the 'pedia. NebY (talk) 17:01, 21 August 2024 (UTC)

Summing up

This RFC has had its 30-day run, so it seems time to wrap it up. Trying to boil the comments above down to editor preferences, my ordered tally is:

Ly, none or km
Pc or ly, km
Ly, pc
Ly, none
Ly, source
Ly, source
Pc, none or ly
Ly, pc
Ly, none or km
Pc, Pm or km
Ly, pc
Ly, pc in prose
Ly, pc
Ly, pc

If I'm counting correctly (feel free to double-check me), out of 14 participants, that's:

Primary: 11 ly, 1 pc or ly, 2 pc
Secondary: 5 pc, 2 none or km, 1 km, 1 none (but pc in prose), 2 source, 1 none or ly, 1 Pm or km
Tertiary: one non-objection to km, some objections in previous discussion

It seems there's a strong preference (79%) for light-year as primary unit, 86% if you count the vote for parsec or light-year.

For the secondary unit, taking the greatest number of supporters for each option (given the "or" votes), there are at most: 5 pc, 4 km, 4 none, 2 source, and 1 Pm. If we add in 3 votes from people who wanted parsec to be the primary unit, that's a solid 8 supporters for parsec, which is 57%, plus the preference for parsec in prose.

So, any objection to closing this RFC with light-year winning for primary unit and parsec for secondary unit? My proposed sub-bullet-point to add to the "Generally, conversions...except:" bullet point in MOS:CONVERSIONS would be the following. -- Beland (talk) 05:23, 6 September 2024 (UTC)

For distances between star systems and galaxies, use "light-years" or "ly" as primary units, with a conversion to "parsecs" or "pc". Link the units on first mention and do not convert to SI units. For larger quantities, use large number words in prose (million or billion but not thousand) and metric prefixes (kly, Mly, Gly, kpc, Mpc, Gpc) in compact contexts. Examples:
- First mention in prose: 34.6 ± 2.3 million light-years (10.6 ± 0.705 Mpc)
  - Wikitext: {{convert|34.6|±|2.3|e6ly|Mpc|sigfig=3|lk=on}}
- Infobox or table: 2.50 Mly (765 kpc)
  - Wikitext: {{cvt|765|kpc|Mly|order=flip|sigfig=3|lk=on}} (use "order=flip" when source uses parsecs)

I think it's a fair summary of the outcome. But since we generally don't give commands, I'd suggest rewording the first two sentences to something like: "For distances between star systems and galaxies, "light-years" or "ly" should be used as primary units, with a conversion to "parsecs" or "pc", but no conversion to SI units. The units should be linked on first mention." Gawaon (talk) 08:24, 6 September 2024 (UTC)

Added to the MOS with your tweaks. -- Beland (talk) 17:26, 6 September 2024 (UTC)

Conversion of non-SI metric units

One part of MOS:CONVERSIONS says "conversions to and from metric units and US or imperial units should be provided". Another part says for units "not part of the SI or US customary systems (e.g. zolotnik), supply a parenthetical conversion into at least SI units". Should the latter part say "metric" or "modern metric" instead of "SI"? I may have been the one to put that in and merely chose the wrong words. I ask now because I came across jansky, which is a non-SI metric unit. It seems a bit silly to convert janskys to 10⁻²⁶ W⋅m⁻²⋅Hz⁻¹, which is apparently more strictly SI.

By "metric units" I assume it's clear we mean anything that's a named combination of SI units or can be related to them with factors of 10, which also includes the liter, hectare, and metric ton. Those three I assume we clearly don't want to convert, but to the degree that they are no longer used, it does seem like we'd want to avoid CGS and MTS units where there are drop-in SI equivalents, like erg or dyne or sthène? -- Beland (talk) 01:18, 30 July 2024 (UTC)

It's a bit tricky since "metric" would be very broad, while "modern metric" and SI seem to be largely treated as synonymous. (Metric system say "The International System of Units is the modern metric system"; similarly, International System of Units calls it "the modern form of the metric system".) Units officially accepted for use with the SI should be fine in general (though I'd still like to see the astronomical unit converted to km, but maybe others will disagree). For others, such as the jansky, it could be decided on a case-by-case basis – that one seems reasonable enough. I think rather than changing the text of that section, adding a note on other acceptable units might be a better solution – to be extended, if the need arises, after a short discussion on this page, or through WP:EDITCON. Gawaon (talk) 06:37, 30 July 2024 (UTC)

I don't think that a "metric unit" is necessarily related to an SI unit by an integer power of 10. The article List of metric units includes multiple examples that do not satisfy this criterion. Examples include the CGS-ESU electromagnetic units statcoulomb and statmho. Are these not metric units? Dondervogel 2 (talk) 07:36, 30 July 2024 (UTC)

CGS is obsolete. I assume it is the reason Beland mentioned "modern metric". Tercer (talk) 08:00, 30 July 2024 (UTC)

Yes that's why I was leaning toward "modern metric", though it's interesting to find out about non-base-10 metric units, so, well spotted!

It does seem like a specific list of exceptions to "convert to SI" is needed for clarity, especially since upon further research there are some units that meet my description that are so obscure I'd probably want to convert anyway. Maybe "metric" in the first sentence should actually be replaced by "SI"?

AU and eV have come up at Wikipedia:WikiProject Astronomy/Manual of Style. I was expecting to have a separate discussion about AU after we finalize a decision for light-years. For electronvolt and dalton, it seems like they are actually too small and fiddly, and are actually well-suited to the domains in which they are used, without conversions that would require scientific notation. If no one objects, I think it would make sense to say units officially accepted for use with the SI (except possibly for AU) don't need to be converted.

List of metric units was very helpful to look through for possible exceptions to the "otherwise convert to SI" rule. I tried to find the ones that would be awkward to convert into SI, either because the combo unit is very complicated, or the non-SI name is very common.

Solar flux unit is complicated but doesn't look like it's used outside of articles about units.
Rad (radiation unit) looks like it could be replaced in our articles with Gray (unit)
Rutherford (unit) could perhaps be replaced with MBq
M for molar concentration seems like a good candidate for leaving unconverted, due to common use.
Rayleigh (unit) is complicated, but only used in a handful of articles; should probably be discussed.
Currently, English Wikipedia articles on some planets have atmospheric pressure given in bar, atm, and Pa. Since 1 bar is exactly 100 kPa, that seems like overkill, and a good topic for the astronomy MOS. Measuring in standard atmospheres is nice because it's an intuitive comparison to Earth, though I guess given that the other scales are calibrated with 1 or 100 at Earth standard, maybe only one of these scales is actually necessary? I don't have a good sense of how well people in metric-using countries know bar and Pa, and if one would be better to use over the other or if they are both fine and could be used based on the field or article history or whatnot. Here in the US, the weather is in inHg, my bike tires are in psi, and I have no intuitive sense of how they relate to each other and vague memories of bar and torr from high school chemistry class. (Hlep!) -- Beland (talk) 08:42, 30 July 2024 (UTC)

The electronvolt and dalton are among the units officially accepted for use with the SI, so I think they should be fine to use without conversion. Molar as mol/L seems fine to me, since the mol is an official and the litre an accepted unit. As for rayleigh, I don't know – there doesn't seem to be any other common unit of photon flux, so it probably needs to be kept? Pressure should preferably be given in or converted to Pa, since that's the standard. Gawaon (talk) 09:18, 30 July 2024 (UTC)

Having lived in several countries that use SI, the kilopascal is the common and only unit for pressure in tires in Southern Africa, Australia and New Zealand. The hectopascal is used worldwide for atmospheric pressure (Canada uses kPa), the USA uses inches of mercury for surface pressure and millibars for upper air pressure. The bar and millibar are deprecated and not SI. What they are trying to do in the MOS is have SI primary for every country except the USA, Britain is a mix. Avi8tor (talk) 10:48, 30 July 2024 (UTC)

Here in Spain bar (and milibar) is used for pressure. In informal speech it is used interchangeably with atm. Pascal only exists in textbooks. Tercer (talk) 13:13, 30 July 2024 (UTC)

I was surprised to see erg (as sole unit) and erg/s (with a conversion to W) in Proxima Centauri, one of the examples in the discussion above. Is that common among astronomers?

Some use hectopascals (hPa) rather than mbar for terrestrial weather, as the values are identical, but in science ant technology generally it's Pa, kPa and Mpa with no glimpse of hPa. For inHg/psi, you probably see barometers go up to about 30 inHg and know standard atmospheric pressure's about 14.7 psi, so 2:1 is good enough for an intuitive relationship? NebY (talk) 17:54, 30 July 2024 (UTC)

Weather for pilots is in hPa worldwide because older altimeters are calibrated to millibars and nothing needs changing. Most airplanes now have a switch to change the display from inHg to hPa depending on where you are on the planet. Avi8tor (talk) 08:59, 31 July 2024 (UTC)

My point is not to develop an intuition about US pressure units, but to point out that for the vast majority of Americans that doesn't exist. -- Beland (talk) 19:20, 31 July 2024 (UTC)

Part of the problem here is that previous discussions have broadly used "SI" as a shorthand for the conventional systems of units used in most of the world outside the US and UK. It was never intended that we strictly use the SI interpretation of the metric system purely for its own sake, regardless of what the rest of the world uses. The people writing this probably weren't thinking of units used by scientists at all. They were thinking of things like Scandinavian miles, pennyweights and chains.

My rule of thumb for scientific articles would be to ask whether the reader (judged e.g. according to WP:ONEDOWN) is likely to be familiar with the unit. If so, no conversion is needed, just link it. If not, then you should convert to a unit that they will be familiar with. Kahastok talk 15:14, 3 August 2024 (UTC)

Sure, which is why a conversion into kilometres (with scientific notation) seems like a good idea. Gawaon (talk) 15:40, 3 August 2024 (UTC)

Depends what you're converting. If you're starting from something in Scandinavian miles, sure. If the starting value is in angstroms, I'd suggest metres or nanometres instead. Kahastok talk 16:56, 3 August 2024 (UTC)

Hehe, sure! Gawaon (talk) 17:37, 3 August 2024 (UTC)

Not all non-SI metric units can easily be converted to SI. For example, in the CGS system, the units of time and of temperature are the second and kelvin respectively, and no conversion is necessary. For some other units, there is a simple conversion by multiplication: the CGS units of mass and of length are the gram and centimetre respectively, and conversion of these to kilograms and metres involves multiplication factors of 0.001 or 0.01 respectively. But anything involving electricity or magnetism is fraught with danger: there are at least two CGS units of electric current, the abampere and statampere, one of which has the speed of light as a term; and one abampere (CGS) corresponds to, but is not equal to, 10 amperes (SI). --Redrose64 🌹 (talk) 15:50, 3 August 2024 (UTC)

All the more reason to always convert them to SI, lest the reader not know what we are talking about. This is a rather abstract concern, though, I have never met anyone that actually wanted to use the electrostatic/electromagnetic CGS units. Tercer (talk) 16:03, 3 August 2024 (UTC)

Draft treatment

Thanks, everyone, for the help in collecting observations about which units are in use around the world. The situation is complicated and I'm not sure what the best solution is for readers that would also satisfy the most editors here. To keep making progress, I've drafted some language, taking Gawaon's suggestion of explicitly listing the units we're talking about. In the process of doing this, I started to realize the great degree to which "core" metric units the general public uses are different than the "core" metric units defined by SI and whatnot, and that affects what level of explanation or linking is needed. That results in somewhat longer lists. Please take my draft only as a starting point for discussion; I don't actually have strong feelings about how these units should be treated and for some of them I just guessed or made an arbitrary choice.

The current text says:

For units of measure that are obsolete, obscure outside of a particular specialty or geography (e.g. furlong), or not part of the SI or US customary systems... supply a parenthetical conversion into at least SI units

We could change "SI" to "metric" in both places and add list sub-items to clarify:

(version 1, edited based on below comments)

Metric units should be commonly known, and commonly-known units approved for use with SI can be used without conversion in science-related articles or as a conversion target in other articles: meter (m), gram (g), second (s), ampere (A), liter (L), Pascal (Pa), hertz (Hz), degrees Celsius (°C), minute (min), hour (h), day (d), degree (of angle, °), volt (V), watt (W)
Metric prefixes used should be commonly known, namely "pico" thru "tera", preferably in commonly-used combinations (e.g. 2,000 kilometers not 2 megameters).
Metric units commonly used in certain fields but less familiar to the general public can be used without conversion in science-related articles or as a conversion target in other articles, as long as the unit name, abbreviation, or symbol is linked on the first instance and the property being measured is clear from context (e.g. that K is for a temperature): kelvin (K), mole (mol), candela (cd), hectare (ha), metric ton (t), joule (J), coulomb (C), radian (rad), steradian (sr), decibel (dB), arcminute (′), arcsecond (″), molar concentration (M), electronvolt (eV), dalton (Da), neper (Np), jansky (jy), gray (Gy), becquerel (Bq), sievert (Sv) tesla (T), farad (F), ohm (Ω), lumen (lm), lux (lx), siemens (unit) (S), henry (unit) (H)
Obscure metric units should be linked and defined in basic SI units on first use: rayleigh (R), katal (kat), weber (Wb)
Metric units other than those listed (e.g. in the CGS or MTS systems) should either be replaced with listed units (e.g. joules instead of ergs), or they should be treated as obscure units in the same way as furlongs.
Some quantities expressed in listed metric units should also be converted into more intuitive field-specific units; see Wikipedia:WikiProject Astronomy/Manual of Style#Units
(Light-year and parsec and astronomical unit will need to be added depending on the outcome of the RFC.)

Later we would either add light-year and astronomical unit or link to Wikipedia:WikiProject Astronomy/Manual of Style, with the specific content depending on the outcome of the RFC. "Pico" thru "tera" are in everyday use according to Metric system, though that may be pushing the boundary of what Americans can cope with in STEM articles where there are no conversions to US units.

-- Beland (talk) 09:10, 14 August 2024 (UTC)

I would recommend using the pipe trick to remove (unit), e.g., [[mole (unit)|]] rendering as mole rather than [[mole (unit)]] rendering as mole (unit). -- Shmuel (Seymour J.) Metz Username:Chatul (talk) 09:56, 14 August 2024 (UTC)

Sure, I wasn't trying to be tidy on the first pass. I just tweaked the draft to pipe as appropriate, not link where linking is not recommended, and show the symbol for each. I kind of grouped the units by topic and frequency and kind of just dropped them in as I came across them. Maybe alphabetical would work better instead? -- Beland (talk) 16:43, 14 August 2024 (UTC)

I needed some extra coffee, so can I check I understand the principles?

Some common/familiar SI units and units approved for use with SI can be used without being linked.
Less familar metric units should be linked on first use.
Obscure metric units should be defined in base SI units on first use.
Only familiar metric prefixes should be used, preferably in commonly-used combinations.
Re conversion, effectively insert thus into the current text or rephrase to this effect: For units of measure that are obsolete, obscure outside of a particular specialty or geography (e.g. furlong), or not part of the SI (or units approved for use with SI) or US customary systems... supply a parenthetical conversion into at least SI units.

Are those the key points, in outline, or have I missed some? — Preceding unsigned comment added by NebY (talk • contribs) 7:13, 14 August 2024 (UTC)

Yes, except on the last item, change "SI" to "metric". -- Beland (talk) 16:20, 14 August 2024 (UTC)

Ah, that would be rather different. Do you mean this? For units of measure that are obsolete, obscure outside of a particular specialty or geography (e.g. furlong), or not metric or US customary units ... supply a parenthetical conversion into at least metric units. NebY (talk) 18:26, 14 August 2024 (UTC)

I should add now, because I might seem to be trying to entrap you, that this would not be wise.

Some units in three variants of the metric system
Quantity	SITooltip International System of Units/MKSTooltip Metre–kilogram–second system of units	CGSTooltip Centimetre–gram–second system of units	MTSTooltip Metre–tonne–second system of units
acceleration (a)	m/s²	gal (Gal)	m/s²
force (F)	newton (N)	dyne (dyn)	sthene (sn)
pressure (P or p)	pascal (Pa)	barye (Ba)	pièze (pz)
energy (E, Q, W)	joule (J)	erg (erg)	kilojoule (kJ)
power (P)	watt (W)	erg/s (erg/s)	kilowatt (kW)
viscosity (μ)	Pa⋅s	poise (P)	pz⋅s

The "metric system", unless specified as SI plus units approved for use with SI, comprises several different coherent variants and a number of, ahem, incoherent units too. It would be unacceptable to provide conversions into most of them. This table, copied from Metric system#Development of various metric systems, shows some. There are also calories, statcoulombs, abamperes (biots), the gauss, maxwells, apostilbs (blondels), skots, brils, stères, and variants on the variants – ampere-turn, international volt, millimetre of mercury (mmHg), metre head (mH₂O), metric horsepower, daraf, debye, demal (a measure of conductivity - our redirect is unhelpful), Einstein (unit) and on, and on. We mustn't go there. The SI units and the units approved for use with SI are the only metric targets we need or want, and have the virtue of being comprehensively documented in reliable sources, fully supported by {{Convert}}, and adopted by many countries and many standards organisations even in places that haven't fully metricated or metrified – NIST, ASME, ANSI and more.

If I've misunderstood you and this is all a straw man - phew! But let's be careful with this. NebY (talk) 20:10, 14 August 2024 (UTC)

You are exactly right; that was what I intended to convey, and I think I failed to do that clearly. Presumably for any units not explicitly listed, we want articles to either not use them or convert them into one of the units listed. I will add another bullet point to make that explicit. Tweaks and further discussion welcome. -- Beland (talk) 22:16, 14 August 2024 (UTC)

Oh, and yes, that was the new wording I intended. -- Beland (talk) 22:18, 14 August 2024 (UTC)

That sentence isn't right yet, or your first bullet isn't. The sentence would require units accepted for use with SI to be converted to SI – litres to cubic metres, degrees Celsius to kelvin, minutes, hours and days to seconds, and so on. It would also stop units accepted for use for SI being sufficient as conversion targets - no converting degrees F to degrees C unless also converted to K. I don't think that's your intention and it's not what your first bulletpoint says. NebY (talk) 13:22, 15 August 2024 (UTC)

I can't tell whether this is meant to apply to scientific articles, or general articles. If the latter, the idea that meters, kilos, and degrees C will be given without conversion is a nonstarter. E Eng 17:09, 14 August 2024 (UTC)
Ah, yes, my wording is definitely muddled. I did not intend to change the circumstances under which units need to be converted, only to say which units we mean by "metric" when we say they can be used without conversion on scientific articles and as conversion targets for articles that use US and imperial units. I will change the phrasing to clarify; further tweaks welcome. -- Beland (talk) 21:54, 14 August 2024 (UTC)
Generally this reads good to me, impressive work! Though I don't quite understand why it says "metric" – wouldn't "SI" work too? Gawaon (talk) 06:28, 15 August 2024 (UTC)
@Gawaon: Whilst all SI units are metric, not all metric units are SI. This has been extensively discussed already. --Redrose64 🌹 (talk) 07:30, 15 August 2024 (UTC)
While that's trivially true, it misses the point. Where in Beland's listing are the non-SI metric units? SI units should usually be preferred, so I just wonder if these non-SI units deserve the treatment suggested for them. Gawaon (talk) 12:57, 15 August 2024 (UTC)
Liters, hours, Daltons, and decibels, for example are non-SI units accepted for use with the SI, though not all of them are based on units of 10 from the base units. Light years, parsecs, or AU may get added to that. Not all of those are what I think of when I think of the metric system; dalton (unit) doesn't even say that unit is part of the metric system, so maybe "metric" isn't the best terminology, either. -- Beland (talk) 16:29, 15 August 2024 (UTC)
Dalton (unit)#Adoption by BIPM already correctly describes it as a non-SI unit accepted for use with the SI and the following sections go into more detail. The lead is unhelpful; we don't need another demonstration that Wikipedia is not an RS so I'll fix that. SI's coherence is one of its great virtues compared to earlier metric systems, but metric units have had many relationships with each other. NebY (talk) 16:50, 15 August 2024 (UTC)

I think it should be fine to talk about "SI units and units approved for use with the SI", especially since we then go on and list all relevant units anyway. So there is no need to mention "metric units". Gawaon (talk) 17:14, 15 August 2024 (UTC)

If I'm understanding correctly, I find myself agreeing with Gawaon (talk · contribs). All non-SI units should be converted to SI, except those units accepted by BIPM for use with SI. Dondervogel 2 (talk) 13:10, 15 August 2024 (UTC)
Just so. We shouldn't require degrees C to be converted to K, or insist that mL be converted to m³. We should normally convert °F to °C not K, and fl.oz. to mL is usually enough,but it would be excessive to start specifying pairs. NebY (talk) 13:33, 15 August 2024 (UTC)
That makes sense. There should also be no requirement to convert logarithmic units like the byte, shannon or decibel to SI. Dondervogel 2 (talk) 18:01, 15 August 2024 (UTC)
Bytes and shannons are units of information and information entropy. As far as I can tell, they cannot be converted to SI units because they are nonphysical, but are also not accepted for use with the SI. Presumably all English- speaking countries use the same units, so I think we don't need to say anything about those. -- Beland (talk) 20:40, 15 August 2024 (UTC)
On second thoughts, some variants of the decibel, like the dBm or dBV, really do need conversion, in these two cases into watts and volts, respectively. Dondervogel 2 (talk) 21:46, 15 August 2024 (UTC)
Beland's fourth bullet Obscure metric units should be linked and defined in basic SI units on first use: rayleigh (R), katal (kat), weber (Wb) is unnecessary and not useful to our readers. Very few who don't understand weber (Wb) will find (kg⋅m²⋅s⁻²⋅A⁻¹) useful; most will find the eruption of gobbledegook into a sentence disruptive. We do want to make the point that Less familar units should be linked on first use, which does sit in the middle of Beland's third bullet about conversion but I think would stand better alone.

That third bullet ends with a long list of units. Do we want such itemisation? It could be summarised instead as "other SI units and units approved for use with SI", "units in SI or approved for use with it", or similar. NebY (talk) 13:56, 15 August 2024 (UTC)

I like that idea. The three units in the last list are used by hardly any articles, so presumably they will explain some amount of more helpful context. If we just say those should be linked like the second list, then the only list we'd need would be the ones that don't need to be linked. -- Beland (talk) 17:29, 15 August 2024 (UTC)

(version 2, edited based on below comments)

Change hatnote to:

Change bullet point and add sub-points:

For units of measure that are obsolete, obscure outside of a particular specialty or geography (e.g. furlong), or not part of the SI/SI-accepted or US customary systems (e.g. zolotnik), supply a parenthetical conversion into at least SI or SI-accepted units. [...remainder of line unchanged...]
- Metric units not part of SI or accepted for use with SI should either be replaced with SI or SI-accepted units (e.g. joules instead of ergs), or they should be treated as obscure units in the same way as furlongs.
Metric prefixes used should be commonly known, namely "pico" thru "tera", preferably in commonly-used combinations (e.g. 2,000 kilometers not 2 megameters).
(Light-year and parsec and will need to be added depending on the outcome of the RFC.)

Under the bullet point "Units unfamiliar to general readers", add:

Commonly-known SI and SI-accepted units that can be used without linking are: meter (m), gram (g), second (s), ampere (A), liter (L), Pascal (Pa), hertz (Hz), degrees Celsius (°C), minute (min), hour (h), day (d), degree (of angle, °), volt (V), watt (W)

Version 2 above is an attempt to incorporate the above comments. If we accept that as a general rule, it implies there is no need to convert AU to kilometers, though we could add an exception for that later. -- Beland (talk) 18:23, 15 August 2024 (UTC)

I'm not sure I like the part about the AU not being converted all that much, but in general, that draft makes a lot of sense! Gawaon (talk) 18:37, 15 August 2024 (UTC)

This is much tighter, easier to read and easier to use, and sound. I like it. I'm not sure we need "(e.g. in the CGS or MTS systems)" - it could be seen as contradictory, because there is a lot of overlap between SI and those two (metres, (kilo)grams, seconds), but that's about the biggest nit I can pick. AU->km might be an exception, but metrology always has edge cases; better to have a clear core. NebY (talk) 11:54, 16 August 2024 (UTC)

Okey, dropped that parenthetical. -- Beland (talk) 04:55, 17 August 2024 (UTC)

What specifically is meant by the "SI/SI-accepted unit and an intuitive field-specific units" clause? I don't think the link to WikiProject Astronomy is all that helpful here. Maybe it would be possible to list the relevant units right here instead? Gawaon (talk) 06:34, 17 August 2024 (UTC)

Wikipedia:WikiProject Astronomy/Manual of Style#Units has like ten additional points, so I thought it would get less out of sync if it only exists in one place? The relevant units would be radiuses and masses of the Sun, Jupiter, Earth, and Moon; luminosity of the Sun; and standard gravity. Maybe better phrasing would be "Some properties of planets and stars need additional conversions; see Wikipedia:WikiProject Astronomy/Manual of Style#Units"? -- Beland (talk) 20:05, 17 August 2024 (UTC)

Frankly I'm not convinced they need to be mentioned here at all. The important point is that at least a conversion into SI units is present; that they are additionally also expressed in alternative units is not forbidden by our rules. So if that's not mentioned here, but only on the Project Astronomy page, there's no conflict. Gawaon (talk) 20:21, 17 August 2024 (UTC)

By "they" do you mean the specific units to be converted to like "mass of the Sun"? I was assuming this MOS page should at least link to any topic-specific advice related to units, for completeness and ease of navigation. -- Beland (talk) 23:14, 17 August 2024 (UTC)

I'm rather sceptical of linking from this page to the WikiProject since it would seem to make the WikiProject's rules an "official" extension of this guideline, which actually they are not. A "See also" hatnote might be more appropriate and would reduce the risk of giving that impression. Gawaon (talk) 06:36, 18 August 2024 (UTC)

Well, if you ask me, they are just as important to follow, because the consequences will be the same - the project will be inconsistent, and people will potentially be upset and potentially revert your edits. But a "see also" link is fine. I'll edit the draft. -- Beland (talk) 15:17, 18 August 2024 (UTC)

Discussion seems to have died down, so I put the revised-as-above version 2 on the live page, except for the light-years part which is still closing out in the above thread. -- Beland (talk) 05:37, 6 September 2024 (UTC)

Jansky and Rayleigh and friends

The above changes have taken care of a lot of cases (hurray!) but as I was tidying up, I realized some units seem to have fallen through the cracks, namely:

jansky (jy), rayleigh (R), katal (kat), weber (Wb)

These seem to be the only metric units not approved for use with SI which are nevertheless still in modern use, and awkward to convert into SI units in a way that is easy to understand when presented briefly. I think the new wording of MOS:CONVERSIONS tells us to treat these units "as obscure units in the same way as furlongs" which would require a conversion to SI units. But given the discussion above, it sounds like we don't actually want a conversion, but would be happy with just linking to the defining articles? If so, I assume we can simply add these as exceptions under the light-year/parsec exception? -- Beland (talk) 18:14, 6 September 2024 (UTC)

I'm not sure about katal and weber (their respective articles claim they are both SI units), but jansky and rayleigh are unfamiliar and should be converted to an equivalent SI unit. Dondervogel 2 (talk) 18:41, 6 September 2024 (UTC)

Ah, you're right; katal and weber are both listed on International System of Units as derived units. I totally missed those on the list. The conversions for the others would be:

1 jansky (10⁻²⁶ W⋅m⁻²⋅Hz⁻¹)
1 rayleigh (1/4π 10¹⁰ photons s^-1 m^-2 sr^-1)

This looks like the "gobbledygook" NebY was objecting to for weber; does that objection also hold for jansky and rayleigh given that unlike weber they are not official SI units? Beland (talk) 19:39, 6 September 2024 (UTC)

The jansky's expression in SI isn't bad, as these things go; it's brief, the units give a fair indication of what sort of quantity's being measured, and the converted values might well be meaningful to those interested. We don't seem to use it often, or if we do we aren't linking it - most of the instances at Special:Whatlinkshere/Jansky seem to be uses of Template:Radio astronomy, and one of the few applications is in the opposite direction a peak X-ray flux density of 2.3×10⁻²³ W/(m²⋅Hz) (2.3×10³ jansky). If someone went wild and inserted SI conversions throughout, at worst it'd cause little offence to editors and little or no difficulty to readers; and it might even be helpful. Let's treat them like furlongs.

The rayleigh's expression looks much more intimidating in either version, using 1/4

π

sr-1 as above or using extended columns of a centimetre cross-section. We link to it in 9 articles, with actual values in only two. IMAGE (spacecraft) has The sensitivity is 1.9 count/second-Rayleigh. Student Nitric Oxide Explorer has The sensitivity of channel A at 130.4 nm is 23 counts/second/Rayleigh and the sensitivity of channel B at 135.6 nm is 26 counts/second/Rayleigh. Is counts/second/rayleigh equal to 4

π

^-1 10^-10 m² · steradian counts per photon?? Is it too late to pretend we never heard about it? NebY (talk) 21:30, 6 September 2024 (UTC)

OK, I've added jansky and rayleigh as affirmative examples of obscure metric units that should be converted to SI. The rayleigh equations didn't make much sense to me either in terms of dimensional analysis or visually, so I'll tag those two articles and rayleigh (unit) itself and ask for some help from experts. -- Beland (talk) 00:25, 7 September 2024 (UTC)

The weber (Wb) is one that I learnt at school (but have had little use of it since). It is the SI unit of magnetic flux, and 1.0 Wb = 1.0 V s, or 1.0 J s C^-1, or 1 × 10⁸ maxwell. --Redrose64 🌹 (talk) 20:56, 6 September 2024 (UTC)

Astronomical units

(The discussion wrapped up and resulted in a change to the MOS.)

Another thread recently concluded that units approved for use with the SI do not need to be converted to SI units. Astronomical units (AU) are approved for use with the SI, but there was some sentiment expressed that they should be converted to SI units.

The RFC on very large distances has concluded that light-years should be primary, with conversion to parsecs and not kilometers or foometers. One big objection to kilometers at that scale was that exponential notation would be required to express those quantities, and many readers would find that difficult to understand. Interplanetary distances are small enough that they can be written in familiar words. Pluto currently does that even in its infobox, and it seems to work OK.

Previous discussion resulted in a decision not to use metric prefixes larger than "tera", because they would not be widely understood; planetary systems extend into the petameters, e.g. the heliopause, though most AU distances probably don't. Articles like Makemake currently use Tm.

Which solution are people in favor of?

Astronomical units are accepted for use with the SI, and don't need to be converted.
Astronomical units should be converted to kilometers using "million", "billion", or "trillion" in both prose and compact environments like infoboxes and tables. Examples:
- 49.3 au (7.38 billion km)
- 121,000 au (18.1 trillion km)
Astronomical units should be converted to meters using metric prefixes. Examples:
- 49.3 au (7.38 Tm)
- 121,000 au (18.1 Pm)
Something else.

Presumably we'd flip to using light-years and parsecs before getting over 9,999 trillion km, possibly even before 999 trillion km. A million AU is about 150 trillion km, and going over 1 million AU could be awkward anyway. -- Beland (talk) 19:06, 6 September 2024 (UTC)

I've nothing against light years or AU, but articles should include a converted value to metres with the appropriate prefix that avoids decimal places 49.3 AU (7,380 Gm). A kilometre is after all 1000 metres. Wikipedia educates, the reader can always link to Giga or another prefix to see what it is. We already use Giga or Gibi for computer storage. Avi8tor (talk) 19:29, 6 September 2024 (UTC)

Hmm, Wikipedia:WikiProject Astronomy/Manual of Style#Units recommends km/s for large velocities, like interplanetary spacecraft. It's a bit harder to compare tens of thousands of km/s to Tm instead of billions of km (though obviously a lot easier than miles). -- Beland (talk) 20:22, 6 September 2024 (UTC)

Your option 2 seems like a good balance: trillion is the largest we'd ever really hit (once around 100,000 au we should switch to ly; might be worth putting that in the guidelines!), and I don't see a large benefit in using metric prefixes for million and billion here. I think the point of a converted value is for people to have a value they can try to compare with ordinary life, and "million km" seems easier to do that with than "billion m". Scientific notation probably isn't worth using in prose but might be in info boxes? - Parejkoj (talk) 20:31, 6 September 2024 (UTC)

NOT #3. The point of the conversion is to move out of specialist-speak. Giving two specialist versions is pointless. Johnjbarton (talk) 23:04, 6 September 2024 (UTC)

Option 2 is clear and useful, and we don't really need to worry about expressing anything in trillions of kilometres. Neptune's only about 30 au (4.5 billion km) from the sun and even the heliopause is about 120 au (18 billion km) out. 121,000 au (1.91 ly) is really an interstellar distance, nearly halfway to the nearest star out here in the boondocks, and I wouldn't expect our sources to be using au then. Not #3, it makes reading too much like hard work. NebY (talk) 23:38, 6 September 2024 (UTC)

I must have been reading something other than the heliopause that's 120,000 AU out and got my numbers mixed up. Oort cloud and a couple dozen other articles do use 200,000 AU, 100,000 AU, and 50,000 AU. Comet, for example, actually converts 50,000 AU to light-years.

We could actually advise, say, anything over 10,000 AU should have AU converted to light-years and not kilometers (that's about 0.16 ly). That starts to become a significant fraction of the distance to the nearest star. It would ease the transition from km to light-years; otherwise short distances have AU+km and long distances have ly+pc and there's no way to directly compare them. -- Beland (talk) 00:58, 7 September 2024 (UTC)

My preference would have been to use AU for small (astronomical) distances and pc (or ly) for large ones, with continuity ensured by always converting to SI. I understand Beland's proposal to be: convert AU to km for short distances, AU to ly for middle distances and ly to pc for long interstellar distances. It's a pig's ear but it's probably the best we can do given the (IMO misguided) decision to avoid converting interstellar distances to SI. Dondervogel 2 (talk) 06:42, 7 September 2024 (UTC)

Ah yes, I was forgetting how great comet orbits can be and the hypothesised extent of the Oort cloud. I'm hesitant about giving advice on a transition point (a little like saying when to use inches or feet) or introducing a third conversion pair. My rule-of-thumb might be that in a planetary or in-system context use au/km, in an interstellar one use ly/pc, and if if it should be put in both contexts then consider using not only one context's pair but also the lead dimension from the other (au/km + ly, or ly/pc + au), but sparingly - and there has to be a better way of putting that. NebY (talk) 12:34, 7 September 2024 (UTC)

I concur that we shouldn't have a transition distance, but rather recommend AU for in-system contexts and ly for interstellar contexts. When both contexts are relevant I think it's better to not try to make a rule; Solar system mixes AU, ly, and km in various places, and I think they do a good job. Tercer (talk) 13:03, 7 September 2024 (UTC)

Should we just say something like "where interplanetary and interstellar scales overlap, it is OK to convert between AU and light-years to make distances comparable"? BTW, for clearly interplanetary distances, were you in favor of AU+km or just AU? -- Beland (talk) 16:55, 7 September 2024 (UTC)

I think that's a good solution. As for AU+km or AU, I don't have a strong opinion. 150 million km is on the edge of what can be intuitively grasped, so it can be useful for some readers. I don't think it's worth the clutter, so I'd rather write only AU. But if some editor wants to add the km conversion I won't bother them about it. Tercer (talk) 19:28, 7 September 2024 (UTC)

Personally I'd favour option 2 as most reader-friendly. However, option 1 follows logically from our general rule that "units approved for use with the SI do not need to be converted to SI units", so it would be a reasonable solution too. Gawaon (talk) 06:42, 8 September 2024 (UTC)

Option #4. None of Options #1-3 are compatible with the use of pc/ly for interstellar distances. To avoid inconsistencies, we need overlap between

large interplanetary distances (in au) and small interstellar distances (in ly/pc), and
large planetary distances (in km) and small interplanetary distances (in au).

The only way I see to achieve both is to convert au to SI for small interplanetary distances and au to ly/pc for large ones. Dondervogel 2 (talk) 09:02, 8 September 2024 (UTC)

Comment To give some examples for how the latter is currently handled: at a predicted minimum distance of 0.051 parsecs—0.1663 light-years (10,520 astronomical units) (about 1.60 trillion km) (from the lede of Gliese 710); about 52,000 astronomical units (0.25 parsecs; 0.82 light-years) from the Sun (from Scholz's Star); and Semi-major axis 506 AU (76 billion km) or 0.007 ly (from the infobox of Sedna). Renerpho (talk) 22:55, 8 September 2024 (UTC)

The second one looks to me like the MOS-preferred style (other than the choice of units) for a triple conversion and something that naturally comes out of {{convert}}, whereas the other two need some tidying up. The quadruple conversion seems like a bit much. -- Beland (talk) 17:20, 9 September 2024 (UTC)

In the case of the solar system article, it became a bit silly to keep converting distance scales from AU to km. The consensus was to use AU throughout, because the AU is intended for interplanetary scales (whereas km is intended for planetary scales). There is a comment in the early part of the article explaining the term, and that is all that is needed. The comparable conversion used on the asteroid articles is AU and Gm. Praemonitus (talk) 21:57, 9 September 2024 (UTC)

From the listed options I would go with Option 1 (just use AU), though I could see giving a conversion to either km or m using scientific notation. I have a pretty strong negative reaction to Gm, Tm, etc; I think that's just SI fetishism. I'm fairly sure those units are used at most sparingly in the wild. --Trovatore (talk) 00:17, 10 September 2024 (UTC)

I'd go with Option 1, but most importantly we should use the modern abbreviation au wherever it appears. Wikipedia's usage has been left inconsistent for too long (including in this thread). Skeptic2 (talk) 11:29, 12 September 2024 (UTC)

Fully agree about consistency of symbol (au, not AU). Let's make sure any new guidance reflects that consensus. Dondervogel 2 (talk) 11:55, 12 September 2024 (UTC)

Is that a proposal to delete "Articles that already use AU may switch to au or continue with AU; seek consensus on the talk page." from MOS:UNITSYMBOLS? I use "AU" in conversation because that's what I learned in as an undergrad, but I have no particular preference. -- Beland (talk) 18:00, 12 September 2024 (UTC)

That was not my intention. I just meant that any new statement about astronomical units should follow existing mosnum consensus, which is to use au for the unit symbol. I can't speak for Skeptic2. Dondervogel 2 (talk) 18:06, 12 September 2024 (UTC)

I have no strong preference between au and AU, but I'm less than convinced that this needs to be uniformized across Wikipedia as a whole. The main thing is that it be consistent within any single article, in the spirit of WP:ARTCON. --Trovatore (talk) 18:09, 12 September 2024 (UTC)

Hmm, well, the existing consensus isn't exactly for "au", it's for "au" except where "AU" is consistently established. I intentionally used "au" in the examples because that seems to be the long-term direction we're going, but for consistency with the other recommendation the examples might need to have a note saying "AU" is OK if used consistently throughout an article. On the other hand, if we're adding or removing conversions across the entire project, that would be a good time to standardize on "au". Dropping the "AU" exception would also result in simpler rules. Either way, I'm going to run a script to find non-compliant instances like I did to enforce the new rule that liter uses a capital "L" symbol.

BTW, I was wondering where consensus for the existing guidance was established, and it appears to be Wikipedia talk:Manual of Style/Dates and numbers/Archive 157#Abbreviation for astronomical unit once again. -- Beland (talk) 18:16, 12 September 2024 (UTC)

I prefer option 1, no conversions or optional conversions. 21 Andromedae (talk) 15:27, 14 September 2024 (UTC)

The use of au in place of AU was recommended by the IAU in 2012 and is now adopted by leading professional journals such as MNRAS, ApJ, AJ, etc. Hence au is the internationally recognized abbreviation and should have been adopted by Wikipedia a decade ago.Skeptic2 (talk) 19:00, 12 September 2024 (UTC)

Summing up au

OK, trying to score the opinions above in a reductionist fashion (correct me if I've gotten anything wrong):

Avi8tor: #3
Parejkoj: #2
Johnjbarton: NOT #3
NebY: #2, NOT #3, for overlap: au+km+ly (and in reverse ly+pc+au)
Dondervogel2: #2 more or less, for overlap au+km, au+ly+pc
Tercer: #1 but #2 OK, for overlap: "where interplanetary and interstellar scales overlap, it is OK to convert between AU and light-years to make distances comparable" rather than a specific rule
Gawaon: #2 but #1 OK
Praemonitus: #1 for solar system
Trovatore: #1 but #2 OK, m with scientific notation OK, NOT #3
Skeptic2: #1

And tallying those up:

#1: 3 first choice, 1 second choice, 1 for solar system context
#2: 4 first choice, 2 second choice
#3: 1 for, 3 explicitly against
#4: 3 in favor of conversion from au to at least ly to provide overlap

It's pretty clear there is consensus against #3, and it looks like there's a weak preference for #2 over #1. Given the reasons people noted for and against converting au to km, it might make sense to adopt #2 but emphasize the existing "excessive" exception, which will result in #1 in places where I expect people feel strongest that au-only is better.

It seems we favor "au" over "AU", so I'll use that in examples. I'm doing some database scans and will ask about removing "AU" as an allowed unit as a separate question once I have some numbers.

It also seems like there's support for having overlapping but not rigidly specified ranges between km, au, and ly, so readers can make appropriate comparisons. Exactly how to do that was a bit unclear, but for the sake of operationalizing this, I'll make a specific proposal. (If people have strong feelings, feel free to discuss.) The previous RFC decided to convert ly to pc, and there might be some objections if ly are used and pc are not (though astronomers also use au). It also decided not to convert between km and ly, partly because of comprehensibility problems with overly-large quantities of km, so maybe we should avoid doing that. Which would also mean the same units would be used no matter whether au or ly were primary, which is kind of nice. So the overlapping units on the high end would be au, ly, and pc, with either ly or au primary.

So, how about adding this as another "Generally...except" bullet point after the "light-years" exception:

Astronomical units (au) should be converted to kilometers (km) using "million", "billion", or "trillion" in both prose and compact environments like infoboxes and tables. When large interplanetary-scale distances overlap with small interstellar-scale distances, convert au to ly and pc, or ly to pc and au (depending on context). Examples:
- 49.3 au (7.38 billion km)
- 121,000 astronomical units (1.91 light-years; 0.59 parsecs)
- .9 ly (0.28 pc; 57,000 au)

and add "articles like Solar system where many interplanetary distances are given" to the list of examples on the "excessive" exception. -- Beland (talk) 03:26, 13 September 2024 (UTC)

Thank you for taking the time to do this. You have captured my position well in your summary. Dondervogel 2 (talk) 05:52, 13 September 2024 (UTC)

I think the last example should read "0.9 ly" since we don't do 0-dropping. Otherwise I like it! Gawaon (talk) 06:11, 13 September 2024 (UTC)

Oh man, well spotted. I have a script to fix that very thing, and am sad to have not noticed that. So make that:

0.9 ly (0.28 pc; 57,000 au)

— Preceding unsigned comment added by Beland (talk • contribs) 17:57, 13 September 2024 (UTC)

Added to the MOS page; further tweaks welcome if anyone notices anything else amiss. -- Beland (talk) 23:00, 13 September 2024 (UTC)

Guidance at APPROXDATE for completely unknown ranges

At risk of instruction creep... currently MOS:APPROXDATE has guidance for various partially unknown date ranges. It doesn't say anything about when everything is unknown, presumably because most editors simply omit it when there's nothing to say. However, it seems there are lists which have say a birth / death range as a standard inclusion per row, and some editors might be tempted to throw in an empty range to mark that the range is not included. There doesn't appear to be MOS guidance for this case, currently.

My suggestion to add:

If both extremes of a range are unknown but a c. or fl. marker is inappropriate, omit the range entirely. Do not use ?–? or ????–????. This is true even if part of a section that normally includes such a range, e.g. a list of people with their birth and death dates. In the rare scenarios where such a range is important to include anyway, use (unknown) or (disputed) if there are referenced scholarly sources saying it is flat unknown or a debate, but do not use these if the dates merely haven't been found in sources consulted so far, such as for obscure people or organizations.

This would basically make "omit it" the default. Thoughts / alternative ideas? Would this be a useful inclusion? (Or alternatively does anyone want to argue we should suggest something different for this case, e.g. using "(unknown)" even when it might be known, just not to the Wikipedia editors at the moment?) SnowFire (talk) 22:04, 10 September 2024 (UTC)

Two points:
- The issue isn't specific to dates or date ranges. It could be any data in a table, so I'm not sure it's a dates-and-numbers issue specifically.
- The advice to say unknown or disputed is good, but my intuition is this isn't something that MOS should opine on (not yet, anyway) -- see WP:MOSBLOAT. Has there been controvery about this on multiple articles currently?

E Eng 23:27, 10 September 2024 (UTC)

I'm honestly not sure if it comes up particularly often. It came up recently at a FLC discussion and I realized there didn't appear to be a "standard" to settle the matter. I'm sensitive to CREEP concerns and if we want to just file this one away as a "wait for a 2nd person to complain", that's fine by me - just figured the first person to raise the matter might still be a useful signal. SnowFire (talk) 09:14, 11 September 2024 (UTC)

Strong oppose the proposal. This comes up all the time if you are writing about medieval and earlier people and events. Obviously you still have include something. It's completely ridiculous to say dating should be suppressed just because we don't know if, for example, someone was born in 1105 or 1109, or some date in between! But there's no point in another finely-tooled set of instructions which most will ignore. MOS:APPROXDATE is already rather too long and over-prescriptive. Johnbod (talk) 15:34, 21 September 2024 (UTC)

Estimated or approximate non-dates?

We generally don't use c. (etc.) for figures other than dates, even in places we would happily use the English word around. Would it be appropriate to explicitly mention options for non-dates such as est. , approx. , and associated templates somewhere? Both the attempted use of circa for non-dates, as well as general confusion on the matter seem at least semi-frequent. Remsense ‥ 论 05:36, 21 September 2024 (UTC)

Circa or c. is mostly used for dates, but there is nothing in its meaning to make it only for dates. Making a new rule (on top of our already too many) seems unnecessary for me. SchreiberBike | ⌨ 00:49, 22 September 2024 (UTC)

I agree there shouldn't be any new provisions, but use of c. or circa for anything but dates, years, etc. will strike readers as very awkward. I'd challenge you to find any non-time usage in high-quality sources. E Eng 01:24, 22 September 2024 (UTC)

That would seem an etymological fallacy to me: the very existence of the narrower convention where it is used only for dates means that other uses trying to treat it as a perfect synonym of around are actively awkward to read; it is a wrong usage. With that made clear, I would object that this is likely MOS creep: approximated and estimated figures are important and common, and editors routinely express a general lack of understanding for how best to present them. Remsense ‥ 论 00:58, 22 September 2024 (UTC)

Wait... you're objecting to your own proposal as WP:MOSCREEP? E Eng 01:24, 22 September 2024 (UTC)

No, sorry: I was objecting to Schreiber's concern of MOSCREEP. Remsense ‥ 论 01:27, 22 September 2024 (UTC)

So you meant to say something more like "I object to the characterization of this as MOSCREEP"? Under that assumption, I disagree (with you), until (per MOSCREEP, which -- ahem -- I wrote) there's evidence that this issue has been a problem on multiple pages. Is there? E Eng 01:44, 22 September 2024 (UTC)

You are correct. There's definitely classes of articles where this is a problem; I'll see what I can do. Remsense ‥ 论 01:46, 22 September 2024 (UTC)

Like the cat who ate some cheese then stood outside a mouse hole, I wait with baited breath. E Eng 02:47, 22 September 2024 (UTC)

Discourage postfix plus?

(motivated by the previous section) If there's any work to be done with combining/rearranging MOS:COMMONMATH and WP:COMMONMATH, can we please also add that "over N" and "at least N" should use the standard notation >N and ≥N respectively (as, for example, the CMOS tells in 3.83 and 12.16) instead of a postfix plus (N+, which is ambiguous, inconsistent with other cases like <N and ~N, and doesn't seem to conform to any reputable style guide)? — Mikhail Ryazanov (talk) Mikhail Ryazanov (talk) 21:29, 7 October 2024 (UTC)

Has this issue come up a lot? E Eng 22:12, 7 October 2024 (UTC)

A while ago I've got a revert with a suggestive edit summary (that particular article has changed a lot since then, but I still stumble upon similar examples from time to time – if needed, I can put some effort to find specific examples). Also, a simple search for insource:/[0-9]\+ / prefix:: yields thousands of results (before timing out), only a small fraction of which are legitimate uses (or poorly formatted binary operations). — Mikhail Ryazanov (talk) 22:54, 7 October 2024 (UTC)

Then the next question is: has time been wasted debating this question on multiple articles, or can they just be fixed on sight without fuss? If the latter, then no new MOS provision is needed, and therefore it is needful that there not be one. E Eng 23:10, 7 October 2024 (UTC)

Misleading shortcut

Wikipedia:Manual of Style/Dates and numbers#Common mathematical symbols indicates that its shortcut is "MOS:COMMONMATH", but in fact MOS:COMMONMATH links to Wikipedia:Manual of Style#Common mathematical symbols (a different section on a different page, although partially covering the same topic), which also indicates "MOS:COMMONMATH" as its shortcut. Perhaps one of them must be renamed. — Mikhail Ryazanov (talk) 00:47, 7 October 2024 (UTC)

@Mikhail Ryazanov: I have traced it to this edit nearly two years ago by SMcCandlish (talk · contribs), which I have reverted. The two redirects MOS:COMMONMATH and WP:COMMONMATH were created on the same day in January 2014 (although about twenty hours apart), the first by BarrelProof (talk · contribs) and the second by Wavelength (talk · contribs) following this discussion. It seems that they were intentionally different - and have remained so ever since. If one of them should be repurposed to match the other after ten years, we would need a WP:RFD. --Redrose64 🌹 (talk) 09:00, 7 October 2024 (UTC)

There must've been something that happened to instigate creation of those on the same day, but I have no recollection of it. —⁠ ⁠BarrelProof (talk) 09:17, 7 October 2024 (UTC)

You'd observed that there are two MOS sections on the symbols and suggested merging them, Wavelength responded that both locations are appropriate and we could have two shortcuts instead, and no-one else said anything. NebY (talk) 11:26, 7 October 2024 (UTC)

Thanks for the refresher. I think the two sections ought to at least mention each other in hatnotes, if not be merged. I just added the mentions. It is confusing that both of them are part of the MOS and both of them are sections of the MOS with the same heading: "Common mathematical symbols". Maybe they should become MOS:COMMONMATH1 and MOS:COMMONMATH2?? Is there some way to express the difference between the purposes of those two? I notice that one of those is part of Wikipedia:Manual of Style/Dates and numbers but says nothing at all about dates and numbers, so I suggest that it be merged into the other one. Mathematics is not synonymous with numbers. That section is about expressing operations and relationships and formatting variable names, not numbers. —⁠ ⁠BarrelProof (talk) 17:50, 7 October 2024 (UTC)

Better with hatnotes, yes. Though mathematics != numbers, MOSNUM seems the natural place where readers might look for guidance on the symbols; after all, the less mathematically sophisticated we are, the more likely we are to think of the operators as things we use with numbers. I'd expected that MOSNUM would be more detailed but there's extra content in MOS too, so that's not a useful distinction. The chatty one and the formal one? NebY (talk) 20:10, 7 October 2024 (UTC)

Usually having "MOS:FOO" and "WP:FOO" go to two different places is fine; the very reason we have the "MOS:" namespace (formerly pseudo-namespace) for MoS shortcuts is that MoS pages were sucking up too many of the mnemonically meanful shortcut strings in which "WP:FOO" would for more editors bring to mind some non-MoS "WP:"-namespace material. Yes, use a disambiguation hatnote as needed; we have those for a reason. However, in this case, both targets are MoS sections, so both shortcuts should go to the same place, presumably the more detailed material. If the stuff at Wikipedia:Manual of Style#Common mathematical symbols is simply a nutshell summary of Wikipedia:Manual of Style/Dates and numbers#Common mathematical symbols (which is probably the case and should be the case) then the former needs no shortcut at all. — SMcCandlish ☏ ¢ 😼 06:04, 8 October 2024 (UTC)

UNITSYMBOLS (1 × 3 × 6 m): “each number should be followed by a unit name or symbol”

MOS:UNITSYMBOLS currently requires a unit symbol after each value when listing dimensions separated by × (“1 m × 3 m × 6 m, not 1 × 3 × 6 m”). Could we have a carveout from this rule, and allow editors to use only a final unit when writing for infoboxes, and perhaps other places where space is limited?

Context: {{Infobox mobile phone}} currently has a preference for listing the dimensions of the product each on a separate line. This, and other parameters, can make the infobox very long. This is especially problematic for pages that cover multiple products or versions of a product; see dimensions in Samsung Galaxy S21 infobox. In order to cut down these infoboxes, we could be using a single line for all three dimensions, but the unit after each value feels unnecessary, and can cause line overflow.

Prior discussion: Wikipedia talk:Manual of Style/Dates and numbers/Archive 145#Repeating units in ranges and dimensions, where the potential for confusion with actually multiplying values was pointed out. I think this is a minor concern in general, but worth considering in prose, or in contexts where the values could be ambiguous. — HTGS (talk) 04:17, 11 November 2024 (UTC)

Where space is limited, it makes sense to present a single compound unit, equal to the product of the separate units. For the example given, the compound unit symbol would be m³. Dondervogel 2 (talk) 12:13, 11 November 2024 (UTC)

Who ever heard of a phone advertised as 5 cc ? People are more interested in it being wide and tall but very thin. This necessitates stating each individual dimension. Stepho talk 22:40, 11 November 2024 (UTC)

No, what Dvogel means is you'd write that a certain phone measures 146 x 71.5 x 7.65 mm³. Having clarified that, I'm bound to say that that would, of course, confuse 99% of our readers. E Eng 22:47, 11 November 2024 (UTC)

Gotcha. As well as confusing most readers, it would also be different to 1 by 3 by 6 m, which is allowed. Stepho talk 23:30, 11 November 2024 (UTC)

To be clear for those playing along at home, while the canonical formuations are 1 m by 3 m by 6 m and 1 m x 3 m x 6 m, MOS currently makes an exception allowing 1 by 3 by 6 m (specifically in the case where all the quantities are in the same unit -- in this case metres), but no corresponding exception allowing 1 x 3 x 6 m. While it may offend purists, I really don't see why the exception shouldn't be extended to that last case as well. Thoughts? E Eng 23:39, 11 November 2024 (UTC)

Thank you for clarifying my intent. And for making me chuckle. LoL

For a 3 dimensional object, one can write either 146 mm x 71.5 mm x 7.65 mm or 146 x 71.5 x 7.65 mm³. I agree the former is clearer, but the latter uses less space, which can be a consideration. There is no difference in meaning.

I guess one could also write 146 x 71.5 x 7.65 mm, but then we have a length, not a volume. It would be clearer to write that length as 79.86 m. Dondervogel 2 (talk) 23:42, 11 November 2024 (UTC)

one could also write 146 x 71.5 x 7.65 mm, but then we have a length, not a volume – Formally perhaps, but you could say the pretty much the same about 146 by 71.5 by 7.65 mm, and yet we allow it. No one will think that 146 x 71.5 x 7.65 mm means the length 79.86 m (i.e. 79860 mm). In context readers will understand it for what it is. I'd like to hear what others think about my proposal. E Eng 23:56, 11 November 2024 (UTC)

Seconded EEng's proposal - simple and clear. Mr.choppers | ✎ 04:36, 14 November 2024 (UTC)

EEng is, of course, correct. At {{convert}} we sometimes are asked how the duplicate mm units can be removed to save space (the trick is to use xx in convert) and we tell them that omitting repeated units is ok if space is limited. May as well make it official. Johnuniq (talk) 05:51, 14 November 2024 (UTC)

EEng is, of course, correct. – Of course -- even Dondervogel says so. E Eng 06:37, 14 November 2024 (UTC)

I also support the proposal. Stepho talk 05:53, 14 November 2024 (UTC)

I thought this was a joke and burst out laughing on a train, which got me a weird look from a fellow passenger. Anyhow, I too support allowing the single unit after x symbols per EEng and John. Toadspike [Talk] 17:31, 18 November 2024 (UTC)

:( — HTGS (talk) 23:34, 18 November 2024 (UTC)

It's tiresome to have to write (and read) units multiple times when multiplication signs are used. Tony (talk) 09:47, 14 November 2024 (UTC)
As the person who proposed this in the first place, I too support EEng’s proposal. I will carry on working on the infobox, and leave the written MOS to others. I imagine the purists might be happy if we left some comment or endnote about making sure the measurements are not potentially ambiguous though?

And, for anyone who cares, there are already pages where this is in sensible use: List of photographic film formats. — HTGS (talk) 23:34, 18 November 2024 (UTC)

Done. E Eng 01:56, 12 January 2025 (UTC)

Sorting of numerical data with mixed units

I need to implement sorting for a table column that mixes different units, but there is no existing guidance on how to do this. For example, the half-life column on Isotopes of thulium uses values with different units, ranging from nanoseconds to years. (For years, NUBASE2020 uses a conversion calibrated to the tropical year: 1 year = 365.2422 d.^[1]) –LaundryPizza03 (d c̄) 04:48, 6 January 2025 (UTC)

Try this:

value	name
100 years	big
2 days	tiny
10 days	tiny
20 days	tiny
10 years	mid
2 years	small

Note that anything less than a year is NumDays/365. Of course, you can choose your own base unit.

See Help:Sortable_tables#Specifying_a_sort_key_for_a_cell Stepho talk 05:04, 6 January 2025 (UTC)

I don't understand your proposal. I'm pretty sure that sort will need numerical sorting with all values converted to a common unit. –LaundryPizza03 (d c̄) 05:24, 6 January 2025 (UTC)

It is more obvious when you look at the wiki mark-up:

{|class="wikitable sortable"
!value!!name
|-
|data-sort-value="100"|100 years||big
|-
|data-sort-value="{{#expr: 2/365.2422}}"|2 days||tiny
|-
|data-sort-value="{{#expr: 10/365.2422}}"|10 days||tiny
|-
|data-sort-value="{{#expr: 20/365.2422}}"|20 days||tiny
|-
|data-sort-value="10"|10 years||mid
|-
|data-sort-value="2"|2 years||small
|}

The data-sort-value is what the sort looks at. In this case I have chosen 1 year as the base unit. So 10 days is 10/365.2422 -> 0.027379092558308 . The rest is just for display. Click on the up/down arrows to sort increasing, sort decreasing or return to original (unsorted) order. Stepho talk 05:35, 6 January 2025 (UTC)

Sure, why not. –LaundryPizza03 (d c̄) 02:10, 7 January 2025 (UTC)

Recent edits

A string of edits by Jc3s5h and JMF. introducing and removing changes to Wikipedia:Manual of Style/Dates and numbers § Common mathematical symbols, raise issues that I believe should be discussed.

The most recent change, permalink/1247903136, has the comment This page does not cover matrix operations., however, I do not see anything in the article to support a restriction to numerical operations.
The most recent change reinstates the link to dot product, despite the comment.
There seems to be disagreement on the division sign.

The questions that I wish to raise are

Should that section mention {{tmath}} or <math>...</math>?
Are vector operations within the scope of the article? Regardless of the answer, the dot and cross products should be treated consistently.
Should there be two new rows for dot and cross product?
Should there be a row for tensor product?
Is obelus unhelpful since it has three forms?
Should the Division sign (U+00F7 ÷ DIVISION SIGN) be deprecated in favor of Slash (U+002F / SOLIDUS)?
Should U+2215 ∕ DIVISION SLASH be explicitly deprecated in favor of Slash?
Should the use of "x" and "*" as multiplication signs be explicitly deprecated in favor of U+00D7 × MULTIPLICATION SIGN?
Should that section show the $L a T e X$ markup for characters in addition to the HTML character entity references?

-- Shmuel (Seymour J.) Metz Username:Chatul (talk) 10:52, 27 September 2024 (UTC)

I think the page should be devoted to general articles, and <math> should be reserved for advanced math and science articles.
Vector operations are not currently in the scope of the project page, and I'm not thrilled about adding them.
Dot product and cross product should certainly not be addressed in the same row as any scalar operation. The multiplication dot should certainly not be linked to the "Dot product" article nor should the multiplication cross be linked to the "Cross product" article.
Tensor products should not be covered in this project page because they're too advanced.
I'm not willing to spend 5 or minutes figuring out what this line means.
The asterisk as a multiplication sign should be limited to articles about computer languages that use it as such.
LATEX should not be mentioned, since we don't use it in Wikipedia. This isn't a style manual for writing outside of Wikipedia.

Jc3s5h (talk) 19:45, 27 September 2024 (UTC)

Tbh, I wondered what this extensive list is doing in the MOS in the first place. Glossary of mathematical symbols does it better. It really needs to be reduced to cover only those symbols that have a styling issue: scalar division and multiplication.

The grade-school division sign should be formally deprecated, for reasons explained at division sign.
The 'ordinary' slash (002F) should be preferred over 2215, same logic as straight quotes and curly quotes.
I prefer U+00D7 × MULTIPLICATION SIGN over x, for biology as well as math but maybe that needs debate.

𝕁𝕄𝔽 (talk) 20:04, 27 September 2024 (UTC)

Comments:

I see no good reason to prohibit using a division sign to express division. That seems absolutely fine. The division sign article seems to say it might be confusing in Italian, Russian, Polish, Danish, Norwegian, or Swedish, but this is the English Wikipedia. We use points as decimal separators also, and we use commas as a thousands separator too, although that might be confusing in other languages.
I also see no good reason to prohibit using an asterisk for multiplication; it seems well-understood, easy to type, unambiguous, and common in practice. I agree with not using "x" for multiplication, although I think it's OK to express "by" relationships for 2x4 lumber, 4x8 sheets of plywood, and 4x4 trucks.
<math>x</math> (i.e., $x$ ) looks different from ''x'' (i.e., x), and those look different from {{math|''x''}} (i.e., $x$ ), at least on my screen, and seeing mixtures of those in the same article can be a bit annoying (especially if they are near each other).

—⁠ ⁠BarrelProof (talk) 21:46, 7 October 2024 (UTC)

Asterisk means convolution (which is somewhat related to the idea of "multiplication" but should not be confused with the usual multiplication). Its use as a substitution for "×" or "⋅" is a bad habit from the old days of poor technology (but it was never used as such in professional typesetting) and has no excuse nowadays. — Mikhail Ryazanov (talk) 22:12, 7 October 2024 (UTC)

Convolution would only be a matter to consider in very mathematically sophisticated specialized contexts. It's not something most people have ever encountered. Even for those who use it, it would often be expressed using summation or integration instead. —⁠ ⁠BarrelProof (talk) 22:21, 7 October 2024 (UTC)

I don't think that this is a good reason to make exceptions to tolerate/promote sloppy typography (moreover, in some computer fonts the ASCII asterisk looks more like a superscript than a binary operator consistent with +, −, = and so on).

I don't think we should feel responsible for how Wikipedia is rendered in all possible fonts. We should remember that everyone is supposed to be able to edit Wikipedia articles. In an article that isn't about mathematics, or at least isn't using it beyond the 10th grade level, f = 1.8 * c + 32 seems basically OK to describe conversion from degrees C to degrees F. It's tricky enough that we tell people to pay attention to the difference between "-", "–", "—", and "−", and to not use italics for the numbers in that formula, although I support those instructions. —⁠ ⁠BarrelProof (talk) 03:37, 8 October 2024 (UTC)

Nobody should complain about otherwise good edits that include "lazy" typography. Those edits are 100% OK and a net improvement to Wikipedia. Other editors who care about typography and MoS can clean up the markup and character choices later. Wikipedia is a collaborative project. Indefatigable (talk) 15:46, 8 October 2024 (UTC)

Using an asterisk to represent multiplication is programming language syntax; I don't think this is common or even well-known among non-programmers. isaacl (talk) 01:47, 20 October 2024 (UTC)

I agree we should discourage use of "*" as a multiplication symbol. I agree it's easy to type, so if one editor writes "y = m*x + c" in an otherwise correct edit, the response should not be to revert that edit, but to replace it with "y = mx + c" or other approved alternative. Dondervogel 2 (talk) 10:40, 20 October 2024 (UTC)

Using an asterisk for multiplication is absolutely known to non-programmers because that's what is used on the number pad on most keyboards in the US. --User:Khajidha (talk) (contributions) 14:28, 12 November 2024 (UTC)

Ah, but which came first - the * key, or its use in mathematical expressions? Forty-some years ago, I was taught that in computer code, the * character was chosen to avoid confusion with the letter x, since the × did not exist in either of the character sets that were in use at the time - ASCII and EBCDIC. It's the same with / vs. ÷ and indeed - vs. −. --Redrose64 🌹 (talk) 18:15, 12 November 2024 (UTC)

* appeared on many (but not all) early typewriters. When not present it was often replaced by a fraction key (1/2, 1/4, etc) Practically every computer terminal from the 1970s onward has a * key - but that's probably due to it being used by Fortran (1957). Early teletype keyboards typically used Baudot code encoding and did not have * - but these were more for telecommunications rather than programming. Fortran was invented at IBM and used punch cards/tape using IBM's BCDIC. The early variations of BCDIC had *, - and / but not +. + was added soon after. My take is that BCDIC tried to encode whatever was commonly used on typewriters - subject to the limitation of using only 64 characters. Fortran then assigned functionality to whatever was in that set. * looked the most like x without being a letter, so it got the job. Stepho talk 23:56, 12 November 2024 (UTC)

It would really behoove participants here, instead of just speculating from the armchair, to take the radical step of doing some research to actually find out the answer. * has been used, in math, to mean multiplication for three hundred years. See the bottom of p. 66 of [18]. E Eng 07:15, 13 November 2024 (UTC)

I didn't mention that paper, because I'm not in the habit of searching through 100-year-old academic journals. Now, 100-year-old magazines is a different matter, witness my stacks of boxes of The Railway Magazine back to 1902 (gaps between 1902 and 1939, complete from 1940 onward). --Redrose64 🌹 (talk) 12:02, 13 November 2024 (UTC)

FORTRAN was a decade earlier than ASCII and EBCDIC. What the first FORTRAN compiler used was the scientific BCD character set of the IBM 704, which replaced the older Percent (%) and Lozenge (U+2311 ⌑ SQUARE LOZENGE) with parentheses. -- Shmuel (Seymour J.) Metz Username:Chatul (talk) 14:35, 13 November 2024 (UTC)

Numerals in a sequence

'Phase 1' or Phase one'? This appears to be a case that's not explicitly covered.

The AP Stylebook recommends using figures for sequences in its section on "Numbers": "Also use figures in all tabular matter, and in statistical and sequential forms", from which I infer that for sequences, such as 'phase 1', figures should be used for clarity and consistency.

Similarly, chapter 9 of The Chicago Manual of Style advises using figures when referring to a sequence.

I propose adding similar explicit advice to this section of the MOS.

-- Jmc (talk) 20:10, 19 October 2024 (UTC)

As usual, what's needed before something's added to MOS is examples of this being an issue on multiple articles -- see WP:MOSBLOAT. Are editors not able to work this out for themselves on individual articles? Anyway, why does the word "Phase" need this in particular? Why not "Section" and "Part" and any other words like that?
The advice from APA and CMS are great if you're making up a new sequence for your thesis, but that's not us. It's hard to imagine an article using a phrase like "Phase 1" or "Phase One" on its own -- that is, other than in imitation of the phrasing of sources. So follow the sources; for example, Economic Stabilization Act of 1970 refers to Phase I and Phase II and Phase III., because that's the form the Act uses. We're not going to override that in the name of consistency with other, unrelated articles. E Eng 22:00, 19 October 2024 (UTC)
To clarify: I'm using 'Phase' purely as an example. The issue of using figures for sequences applies to any sequence. including 'Section' and 'Part' - and other examples: "Game 3", of a sequence of nine; 'Chapter 9' of a sequence of 24; 'Week 4' of a limitless sequence.

I raise this issue in the context of differing editorial practices in the British Post Office scandal article, where both figures and words have been used to reference the same phases and weeks of the inquiry. I sought guidance from the MOS and found none.

I'd be content to follow the sources, without adding bloat to the MOS, if I could be confident that that's an accepted stylistic convention in this instance. -- Jmc (talk) 22:27, 19 October 2024 (UTC)
Such names are very often established by authoritative sources and constitute proper names; we should follow the sources rather than renaming them. Per EEng, we only need a MOS guideline if our sources don't provide clear names and either there is dissent among editors or consistency across articles would be of significant benefit. In the Post Office case, I see the phases have been titled Phase 1, Phase 2 etc by the inquiry[19] so unless the inquiry's inconsistent, we can follow that source. Still, I see that this is a live issue at that British Post Office scandal article, so it would be wrong to establish a new guideline or issue some sort of MOS talk-page ruling without the knowledge of the other editor; pinging MapReader. NebY (talk) 14:56, 20 October 2024 (UTC)
Between May 1966 and December 1989, multi-episode Doctor Who stories could have titles in any of the four combinations of (i) "Episode ..." or "Part ..."; (ii) numbers as figures or as words. The decision as to which format to use was probably in the hands of the series producer, but in our articles about each story, we give the actual title shown on screen - except that where the on-screen title is all-capitals, we reduce it to title case. Certain Doctor Who reference books do the same, so we're following the sources. --Redrose64 🌹 (talk) 18:18, 20 October 2024 (UTC)
The question raised was "differing editorial practices in the British Post Office scandal article". Sounds like a matter of internal consistency, which is different. For all manner of things -- this being one IMO -- we might not need consistency among articles, but it does look bad within articles. Surely we already have a rule addressing that general issue tho? Herostratus (talk) 13:24, 21 October 2024 (UTC)
I think we don't. In articles on TV series it's common to have expressions like "season 3" and "episode 7", which seem to go against our current wording (use words for numbers below 10). Gawaon (talk) 16:37, 21 October 2024 (UTC)
It is indeed a matter of internal consistency and it does look bad, as Herostratus says. Within the one article (British Post Office scandal), we have (e.g.) both "Phase 3 hearings" and "Phases five and six". Is there in fact a rule addressing this general issue? -- Jmc (talk) 18:47, 21 October 2024 (UTC)

From Wikipedia:Manual of Style/Dates and numbers#Numbers as figures or words: "Comparable values nearby one another should be all spelled out or all in figures, even if one of the numbers would normally be written differently." Unless you are dealing only with series with fewer than 10 seasons each with fewer than 10 episodes, it is more in line with MOS to give all season and episode numbers in digits rather than words. --User:Khajidha (talk) (contributions) 13:15, 22 October 2024 (UTC)
True, but series with less than ten seasons aren't all that rare, and there are also miniseries with less than ten episodes. Gawaon (talk) 16:39, 22 October 2024 (UTC)

Whether or not it's in line with MOSNUM, we frequently – I suspect in the vast majority of cases – give series/season and episode numbers in digits. I've been dipping into Wikipedia:Good articles/Media and drama#Television. Articles on individual episodes do routinely begin e.g. " the ninth and final episode of the first season" but with digits in the infobox. Articles on a season/series list episodes using digits, and articles on a show list series/seasons and episodes with digits, regardless of whether there are more or less than ten, in keeping with the examples in Wikipedia:Manual of Style/Television#Episode listing. Articles are often titled <show> season <n> where n is a digit, never a word, in accordance with Wikipedia:Naming conventions (television)#Season articles. Sampling our WP:Featured articles#Media, I see the same treatment in titles, infoboxes, and listings.
I very much doubt that editors would accept changes to those FAs and GAs to bring them into line with MOS:NUMERAL, that FA and GA assessors will start to apply MOS:NUMERAL in such cases, that any move requests would succeed, or that MOS:TV and WP:TVSEASON will be brought into line with the current MOS:NUMERAL. Changing MOS:NUMERAL might be easier. NebY (talk) 08:20, 23 October 2024 (UTC)
I agree, a small addition to MOS:NUMERAL might be a good thing. Gawaon (talk) 17:00, 23 October 2024 (UTC)

Your final sentence doesn't follow from your statement. It would be more in keeping with the MOS to give all in words. MapReader (talk) 11:16, 23 October 2024 (UTC)
Generally concur with EEng and NebY. It's clear that certain conventions adhere strongly to certain things, and these conventions will be readily apparent from the source material about those things. WP is not in a position to impose an artificial WP-invented consistency on them that makes no sense for those familiar with the subject (e.g. referring to "issue number seven" of a comic book or "the three ball" in a game of pool). Where nothing like a consistent convention can be observed for the topic at hand, then MOSNUM already provides us with a default to fall back to: use "one" through "nine", then "10" onward. This is the case with centuries, for example. There is no overwhelming source preference for either "third century BC[E]" or "3rd century BC[E]" in reliable sources. (Books tend to prefer the former, journals use the latter more than books do because journal publishers are more interested in compression/expediency. Scroll through first 10 pages of GScholar resuls here and see how much variance there is, and how frequent the numeral style is compared to "traditional" spelling-out. That said, GScholar searches do include some books as well as journals.) Following our default system, we naturally end up with "third century BC" and "12th century BC". (Of course, our material doesn't perfectly follow this; our editors are human, not robots. Well, mostly.) — SMcCandlish ☏ ¢ 😼 15:04, 24 November 2024 (UTC)

μs vs us

Which style I should use for micro seconds? Does μs relative to "Do not use precomposed unit symbol characters"? DungeonLords (talk) 04:44, 30 October 2024 (UTC)

The 2 characters "μ" and "s" are just fine. The precomposed symbols advice is to guard against particular fonts that combine them into a single character because many software readers for the sight impaired do not know all of these symbols. Stepho talk 04:53, 30 October 2024 (UTC)

But do use μ, not "u". The latter was something of an early-Internet halfassed approach, but we have Unicode now. — SMcCandlish ☏ ¢ 😼 15:09, 24 November 2024 (UTC)

Day, date month format

Greetings and felicitations. I assume that such constructions as "Wednesday, 24 February" are discouraged, but I can't find it in the text or the this page's archives. (The comma seems unnecessary to me.) May I please get confirmation or refutation? —DocWatson42 (talk) 04:28, 4 November 2024 (UTC)

MOS:DATEFORMAT and MOS:BADDATE cover the allowed and disallowed formats. Unless the day of the week is vitally important then we leave it out. Stepho talk 06:16, 4 November 2024 (UTC)
This specifically regards the "Hadaka Matsuri" article, and its Konomiya Hadaka Matsuri infobox, which includes the days of the week. —DocWatson42 (talk) 07:40, 4 November 2024 (UTC)
Ah, the mysterious East. E Eng 08:06, 4 November 2024 (UTC)
Salutations and hugs and kisses to you too.
- If your question is whether day-of-week should be gratuitously included with dates for no particular reason, the answer is No. That is, if the day-of-week is somehow relevant to the narrative, sure, include it, but otherwise no.
- Assuming we're in some situation where (per the preceding) inclusion of day-of-week is indeed justified, maybe your question is how to append the D.O.W.
  - If the date is February 24 or February 24, 2024, then without doubt the right format is Wednesday, February 24 or Wednesday, February 24, 2024.
  - According to "Elite editing" [20] (whoever they may be -- search the text "inverted style" on that page), the corresponding answers for 24 February and 24 February 2024 are Wednesday, 24 February and Wednesday, 24 February 2024. To me that does seem right -- Wednesday 24 February 2024 (all run together, no commas at all) seems intolerable.

The question naturally arises as to whether MOS should offer advice on all the above. My answer, as usual, is provisionally No, per WP:MOSBLOAT. E Eng 08:02, 4 November 2024 (UTC)

Looking at the article, the date is the 12th day of the Chinese year and the day of the week has no significance. I would remove the day of the week from all those dates in the infobox. For what it's worth, I spent most of the 1990s in Hong Kong/China. Major holidays based on the Chinese calendar treat the day of the week in the same way that we treat the day that Christmas falls on. Stepho talk 09:18, 4 November 2024 (UTC)

Okay—will do. Thank you both. ^_^ —DocWatson42 (talk) 09:21, 4 November 2024 (UTC)

The new 18th edition of The Chicago Manual of Style gives advice about commas in dates in ¶ 6.14. When giving examples they mostly give examples with words after the end of the date so the punctuation at the end of the date is illustrated. Some examples:

The hearing was scheduled for 2:30 p.m. on Friday, August 9, 2024.
Monday, May 5, was a holiday; Tuesday the 6th was not.

Jc3s5h (talk) 16:56, 4 November 2024 (UTC)

Concur with EEng on avoiding adding a rule about this, as more WP:MOSBLOAT. It's just a matter of basic writing sense, basic comma usage in competent English. Our MoS's purpose is not that of CMoS or Fowler's, trying to answer every imaginable usage question. Just those that have an impact on reader comprehensibility and/or recurrent editorial strife. — SMcCandlish ☏ ¢ 😼 15:18, 24 November 2024 (UTC)

Spacing with percentage points

A question regarding spacing of percentage point (pp) usage. I have always assumed there is no space between the number and pp (e.g. 5.5pp not 5.5 pp), on the basis that you wouldn't put a space between a number and a percentage sign (5% not 5 %). There is no reference to this in the MOS, but the percentage point article uses it unspaced. It might be good to have it clarified in the MOS as I see regular changes adding spacing, which I am not sure is correct. Cheers, Number 5 7 23:49, 5 November 2024 (UTC)

MOS:PERCENT says "omit space". Stepho talk 23:54, 5 November 2024 (UTC)
Perhaps I am missing something, but as far as I can see, it says to omit space when using the percentage symbol (%) but nothing about when using pp? Number 5 7 00:21, 6 November 2024 (UTC)
Apologies, I missed the "point" word in your question. Stepho talk 01:49, 6 November 2024 (UTC)
% is essentially a constant factor (.01), but pp is more like a unit so my intuition says it should be spaced. I note that the basis point article uses a space before bp (mostly, anyway). I'll be interested to hear what others think. E Eng 18:23, 6 November 2024 (UTC)
You've got this back to front. Percent (%) is a standard unit symbol and should be spaced, whereas pp is a made up abbreviation, meaning you can put it anywhere you want, space or unspaced. I know MOSNUM says otherwise, which is WP's prerogative. In other words, if we need a rule, let's make one up and apply it, but there's no logic involved. Dondervogel 2 (talk) 21:06, 6 November 2024 (UTC)
Dondervogel, "Percent (%) is a standard unit symbol and should be spaced". Huh? It's not an ISO unit symbol, is it. No spacing in English, unlike French. On pp, I agree with EEng: space it. Tony (talk) 11:10, 8 November 2024 (UTC)
Absolutely. When it comes to peepee, always space it [21]. E Eng 21:36, 8 November 2024 (UTC)
Yes, "%" is an ISO standard unit symbol. Dondervogel 2 (talk) 12:45, 8 November 2024 (UTC)
What is it the unit of? Gawaon (talk) 13:14, 8 November 2024 (UTC)
Nothing. It's a dimensionless quantity. To the original q: I don't see "pp" used often, in fact rarely. It's probably better written out in full on first use, and if there are subsequent uses, follow the guidance at MOS:ACRO1STUSE. --Redrose64 🌹 (talk) 19:58, 8 November 2024 (UTC)
It's used widely in election infoboxes where there isn't space to write it out. Number 5 7 22:25, 8 November 2024 (UTC)

I will answer Gawaon's valid question in two parts. The first part is a quotation from ISO 80000-1:2009 (emphasis added)
In some cases, per cent, symbol %, where 1 % := 0,01, is used as a submultiple of the coherent unit one.

EXAMPLE 4

reflection factor, r = 83 % = 0,83

Also, per mil (or per mille), symbol ‰, where 1 ‰ := 0,001, is used as a submultiple of the coherent unit one.Since the units “per cent” and “per mil” are numbers, it is meaningless to speak about, for example, percentage by mass or percentage by volume. Additional information, such as % (m/m) or % (V/V) shall therefore not be attached to the unit symbol %. See also 7.2. The preferred way of expressing, for example, a mass fraction is “the mass fraction of B is w B = 0,78” or “the mass fraction of B is wB = 78 %”. Furthermore, the term “percentage” shall not be used in a quantity name, because it is misleading. If a mass fraction is 0,78 = 78 %, is the percentage then 78 or 78 % = 0,78? Instead, the unambiguous term “fraction” shall be used. Mass and volume fractions can also be expressed in units such as µg/g = 10-6 or ml/m3 = 10-9.

Notice the deliberate space between numerical value (e.g., 83) and unit symbol (%). Dondervogel 2 (talk) 22:10, 8 November 2024 (UTC)

The second part is a partial retraction, quoting from ISO 80000-1:2022, which supersedes the 2009 document:
If the quantity to be expressed is a sum or a difference of quantities, then either parentheses shall be used to combine the numerical values, placing the common unit symbol after the complete numerical value, or the expression shall be written as the sum or difference of expressions for the quantities.

EXAMPLE 1

l = 12 m - 7 m = (12 - 7) m = 5 m, not 12 - 7 m

U = 230 ⋅ (1 + 5 %) V = 230 ⋅ 1,05 V ≈ 242 V, not U = 230 V + 5 %

The space is still there between numerical value (5) and percentage symbol (%), but I could not find an explicit reference to "%" as a unit symbol. I'm unsure how to interpret that change, but I'll report back here if I find further clarification. Dondervogel 2 (talk) 22:16, 8 November 2024 (UTC)

I found this in NIST Special Publication 811
In keeping with Ref. [4: ISO 31-0], this Guide takes the position that it is acceptable to use the internationally recognized symbol % (percent) for the number 0.01 with the SI and thus to express the values of quantities of dimension one (see Sec. 7.14) with its aid. When it is used, a space is left between the symbol % and the number by which it is multiplied [4: ISO 31-0]. Further, in keeping with Sec. 7.6, the symbol % should be used, not the name "percent."

Example: xB = 0.0025 = 0.25 % but not: xB = 0.0025 = 0.25% or xB = 0.25 percent

Note: xB is the quantity symbol for amount-of-substance fraction of B (see Sec. 8.6.2).

Because the symbol % represents simply a number, it is not meaningful to attach information to it (see Sec. 7.4). One must therefore avoid using phrases such as "percentage by weight," "percentage by mass," "percentage by volume," or "percentage by amount of substance." Similarly, one must avoid writing, for example, "% (m/m)," "% (by weight)," "% (V/V)," "% (by volume)," or "% (mol/mol)." The preferred forms are "the mass fraction is 0.10," or "the mass fraction is 10 %," or "wB = 0.10," or "wB =10 %" (wB is the quantity symbol for mass fraction of B—see Sec. 8.6.10); "the volume fraction is 0.35," or "the volume fraction is 35 %," or " φB = 0.35," or "φB = 35 %" (φB is the quantity symbol for volume fraction of B—see Sec. 8.6.6); and "the amount-of-substance fraction is 0.15," or "the amount-of-substance fraction is 15 %," or "xB = 0.15," or "xB = 15 %." Mass fraction, volume fraction, and amount-of-substance fraction of B may also be expressed as in the following examples: wB = 3 g/kg; φB = 6.7 mL/L; xB = 185 mmol/mol. Such forms are highly recommended (see also Sec. 7.10.3).

In the same vein, because the symbol % represents simply the number 0.01, it is incorrect to write, for example, "where the resistances R1 and R2 differ by 0.05 %," or "where the resistance R1 exceeds the resistance R2 by 0.05 %." Instead, one should write, for example, "where R1 = R2 (1 + 0.05 %)," or define a quantity Δ via the relation Δ = (R1 - R2) / R2 and write "where Δ = 0.05 %." Alternatively, in certain cases,the word "fractional" or "relative" can be used. For example, it would be acceptable to write "the fractional increase in the resistance of the 10 kΩ reference standard in 2006 was 0.002 %."

As with ISO 80000-1:2022, there is always a space between numerical value (e.g., 35) and the percentage symbol (%), but no mention of % as a unit symbol. Dondervogel 2 (talk) 22:38, 8 November 2024 (UTC)
there is always a space between numerical value (e.g., 35) and the percentage symbol (%) – Maybe in NIST-world, but not here on Wikipedia (see MOS:PERCENT), so I don't see how any of that helps us with the issue at hand. E Eng 23:29, 8 November 2024 (UTC)
I was correcting a misconception that % is not a unit symbol when it is. At least it was until 2022. I find it best not to leave incorrect statements unchallenged or they take on a life of their own. Dondervogel 2 (talk) 00:24, 9 November 2024 (UTC)
Um, OK, but you do realize that WP does not follow NIST's advice about spacing it, yes? E Eng 00:44, 9 November 2024 (UTC)
Yep, and I wasn't trying to change that. My contributions have been to
correct a factual error (yours)

respond to questions from Tony and Gawaon

I have not weighed in on the main thread regarding percentage points because I don't expect my opinion (based not on NIST's utterings but on the ISO standards on which they are based) to be taken seriously, so why would I waste my e-breath? Dondervogel 2 (talk) 09:41, 9 November 2024 (UTC)
It is not conventional to space "%" in English. Nearly no publishers do this, and our MoS doesn't say to do this or incidentally illustrating doing this, so don't do this. "pp" here is a unit abbreviation for percentage point ("the unit for the arithmetic difference between two percentages)", so space it. % is not a unit abbreviation/symbol, but a quantity symbol, so it's in a different class. It's more like the ~ in "~5 ml". That the spelled-out equivalent "approximately", like the spelled out "per[]cent", is spaced apart from the numeral is irrelevant. — SMcCandlish ☏ ¢ 😼 15:24, 24 November 2024 (UTC)

Do we have to convert inches for wheels?

I see people adding conversions to mentions of screen sizes and wheel dimensions - is this really necessary? Even in Germany or New Zealand, automobile and bike wheels are universally referred to by inches; rim diameters are expressly defined in inches in the EU regulations. To me, adding conversions for these types of dimensions adds unnecessary clutter, harming readability for no return whatsoever. I haven't read the entire MOS today, apologies if I missed a mention of these situations. Mr.choppers | ✎ 17:24, 13 November 2024 (UTC)

It looks like sizing bike wheels in inches is not universal. I see many charts in the I-net such as this that use both metric and imperial/American units for bike wheels and tires. Whether the convert template handles them correctly is another issue. Donald Albury 17:43, 13 November 2024 (UTC)

On the matter of wheel sizes, not all are inches. See this post and my reply. Even for a conventional non-Denovo wheel, the dimensions are a bastard mixture: "195/65 R 15" means a tyre that is 195 mm wide on a 15-inch rim. --Redrose64 🌹 (talk) 19:10, 13 November 2024 (UTC)

Yes, there is the Michelin TRX and the Denovo. Just as we wouldn't convert the "195" when we write 195/60 R15, I don't think we ought to convert the diameter either. I would treat all of these tire dimensions as one would nominal measurements, rather than inserting unnecessary templates. Bicycle tires, meanwhile, proved more varied than I was aware of. Mr.choppers | ✎ 04:33, 14 November 2024 (UTC)

I agree with Mr.Choppers on this subject. I think wheels sizes on cars are a compromise between the USA and the rest of the world. There are metric rims on older vehicles but pretty rare on new vehicles. Avi8tor (talk) 11:40, 14 November 2024 (UTC)

@Avi8tor: - I was actually triggered by you converting screen dimensions, but five minutes online showed me that the modern world has indeed begun dropping the use of inches for screens. My gut was wrong. Mr.choppers | ✎ 13:36, 14 November 2024 (UTC)

Many people around the planet know only millimetres, so it makes sense to have both. I notice in France the data information on television screen size have it in both inches and millimetres. Avi8tor (talk) 17:57, 16 November 2024 (UTC)

I agree with Aviator, who didn't mention that aviation uses "feet" for altitude—needs conversion in my view. Tony (talk) 07:30, 22 November 2024 (UTC)
I thought that "feet" used for altitude is not a measure of distance but of pressure, so perhaps it should be converted to pascals first. I'm not saying one should not then convert to metres too - only that the conversion would need some care. Dondervogel 2 (talk) 22:06, 22 December 2024 (UTC)

Unit formatting

Are any of these formats correct?

a 10-cm blade
a 10 cm blade
a 10-cm-long blade
a 10 cm-long blade
a ten-cm blade
a ten-cm long blade

And why numbers are not spelled out before unit symbols, and why unit symbols are used more with metric than imperial units, where unit names are typically written in full? --40bus (talk) 13:56, 22 December 2024 (UTC)

In answer to your first question I suggest choosing between "a 10 cm blade" and "a ten-centimetre blade".

To the second, there is no internationally accepted standard describing symbols for the imperial unit system. Perhaps that is the reason. Dondervogel 2 (talk) 14:05, 22 December 2024 (UTC)

You can also consult our {{convert}} template which deals with all these edge cases: {{convert|10|cm|adj=on|abbr=on}} produces 10 cm (3.9 in), per MOS:UNITSYMBOLS.

Also, is there a reason you're not just consulting the MOS directly? It more or less covers your questions so far. Remsense ‥ 论 15:07, 22 December 2024 (UTC)

This is possible to output: {{convert|10|cm|adj=on|abbr=on}}, and it produces: ten cm (3.9 in). So, why it is not used? And a sixth question, why fractions are not usually used with metric units? Fractions would be useful indicating repeating decimals, such as one-seventh of a meter, as things like "0.142857142857... m" or "0,142857 m" would look ugly, so 1⁄7 m would be only option. --40bus (talk) 23:13, 22 December 2024 (UTC)

Do you have a real world example illustrating your concern? Dondervogel 2 (talk) 23:22, 22 December 2024 (UTC)

How would 1⁄7 be the "only option"? You yourself just used the obvious other one: simply writing "one-seventh", which isn't broken in any way, and is probbaly easier to read for most people, than 1⁄7, which can mess with line height. It actually copy-pastes as 1⁄7, with inconsistent display on various systems. The use of the Unicode fraction-slash character is interpreted by some OSes, including my Win11 box (but not my Mac, or any Linux I can remember using), as an instruction to superscript the 1 in nearly unreadably tiny font and do the same to 7 but as a subscript. (Win11 even does this to me in a <code>...</code> block!) I'm not convinced we should have that template at all, since the Internet has done just fine with 1/7 for decades. Regarding the other material, Remsense is correct that there's a standard way of abbreviating metric units (and there's also a lot of systemic enforcement of that), but there isn't an entirely standardized approach to other units (perhaps better called "American traditional" at this point), and they are often unabbreviated in the real world. So, despite MoS providing a standard way of abbreviating them (based on ANSI or whatever, I don't remember), there's less editorial habit and desire to bother with it, while editors steeped in metric (everyone but Americans) are habituated to the short symbols. Nothing's really harmful about any of this, with regard to reader comprehension, so we have no need to firmly impose a rigid rule to do it this way or that. (We do have such a rationale for settling on particular American/"Imperial" unit abbreviations, though, since use of conflicting ones from article to article would be confusing for readers and editors alike, and some of them found "in the wild" are ambiguous and conflict with actual standards (e.g. using "m" to mean 'miles' instead of 'metres/meters'). As for the original question, yes it's "a 10 cm blade", and the output of {{convert}} is MOS:NUM-compliant. A construction like this is taken as an strongly conventionalized exception to the MOS:HYPHEN rule of hyphenating compound modifiers (writing "a 10 cm-blade" or "a 10-cm-blade" isn't really any clearer, and probably less so). In long form it would be "a ten-centimetre-long blade" and Dondervogel is correct that "-long" would usually be omitted for concision, unless it was necessary to indicate length versus width of something (which isn't the case with a knife or sword or whatnot, but would be with a shipping box). — SMcCandlish ☏ ¢ 😼 07:12, 23 December 2024 (UTC)

Which era?

I'm inviting fellow editors to figure out whether Religious perspectives on Jesus should use BC / AD or BCE / CE. The issue is that the article mixes eras and when I went back to see which was first, I saw it originally used "BC/BCE" and it stayed like that for years. The thread: Talk:Religious perspectives on Jesus#BC BCE AD CE. Thanks! — Preceding unsigned comment added by Masterhatch (talk • contribs)

MOS:ERA applies so status quo ante should apply. (FWIW, Judaism and Islam have religious perspectives on Jesus of Nazareth, so the neutral style seems entirely appropriate.). --𝕁𝕄𝔽 (talk) 00:18, 22 December 2024 (UTC)

Agreed on the last part. As for the procedural matters, all of our MOS:VAR principles ultimately default/fallback to the style used in the first non-stub version that used one of the competing styles, if consensus fails. MOS:STYLEVAR is the general principle, the root rule: Don't change from one acceptable style without a very good reason. If there is or you expect resistance, discuss to establish consensus. If you don't get consensus for your change (i.e., there is consensus against you), it stays the status quo ante. If there's no consensus on which would be better (which is often the case and likely the one in this case), then use the version established earliest. For particular things covered by MOS:DATEVAR, MOS:ERA, MOS:ENGVAR, WP:CITEVAR, we simply reiterate this principle and process more topically, and these ones also basically resolve to an additional rule: don't change that particular kind of style without establishing consensus first even if you're sure you've got a good reason and don't think there should be resistance.

The STYLEVAR process actually sometimes (namely when there's clearly no firm consensus in favor of the status quo ante, either) overrides the usual Wikipedia status quo ante principle, which in practice amounts to "fall back to whatever the discussion closer thinks is more or less a pretty long-term status quo". That usually works for a lot of things, but for these "I will win my Holy Style War or die trying" tedious cyclic bikeshedding typographic disputes, it has proven unworkable, because the dispute lives on and on, simply shifting in stages to: what constitutes a status quo; how long is long enough; whether interruptions in the use of the alleged status quo have reset its tenure; whether this *VAR-imposed consensus discussion was followed when the alleged status quo was imposed; if not, then whether that imposition pre-dated STYLEVAR requiring it; and yadda yadda yadda. There's just no end to it, because it's too often a super-trivial but deeply obsessive PoV-pushing exercise grounded in prescriptivist emotions (mixed sometimes with nationalist, or socio-politically activistic, or my-profession-vs.-yours, etc.). The style-war-ending default of falling back to the first major edit that established one of the competing styles is arbitrary (in both senses), but it is the end of it, and we move on to something more productive.

For this particular article: If "it originally used 'BC/BCE'" in the original post isn't a typo, and really does mean that the style was mixed from day one, then that's a rare edge case, and JMF's "status quo ante should apply" is probably the only reasonable approach. (Even from an excessively proceduralist viewpoint: If STYLEVAR and its application ERAVAR impose an overriding principle that in this case cannot actually be applied, then the default necessarily must be the normal Wikipedian status quo ante principle, even if for matters like this it tends to lead to re-ignition of the dispute again in short order. Not every solution is perfection.) — SMcCandlish ☏ ¢ 😼 12:02, 23 December 2024 (UTC)

But what would be the status quo ante in this case? Surely you can't mean the mixed BC/BCE style? Gawaon (talk) 08:56, 24 December 2024 (UTC)

RfC Indian numbering conventions

There is consensus to continue using crore and lakhs when appropriate.

Most participants also generally agreed with SchreiberBike's conditions (or a variant) - Always 1) link it on first use, 2) include what it is a measure of (rupees can not be assumed), 3) also include conventional numbering, and 4) allow it only in articles about the subcontinent.

However, this RFC suffered from structural issues that a precise wording isn't agreed on yet. Any changes from status quo should go through a clearer future discussion or RFC on just that.

(non-admin closure) Soni (talk) 22:02, 24 December 2024 (UTC)

The following discussion is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

I am revisiting an issue that was last brought up 6 years ago here and settled without a strong consensus.

I think we should avoid using Indian numbering conventions unless it is needed for context. For instance, if we want to list the box office take of an Indian movie, don't use "crore", use "millions". This isn't about disrespecting a culture, it's about using internationally favored notation and unit conventions. We should use "millions" instead of "crore" for the same reason we favor meters over feet. There is no reason that India-related articles should be an enclave of Indian conventions. People who are not Indian will struggle with these things, it will weaken Wikipedia's role as an information tool for everyone.

This is not the same thing as currency. It is appropriate to list an Indian movie's box office take in rupees. Providing a US$ conversion is optional, but a good idea since the US dollar is widely used around the world as a reserve currency. But write it as "millions of rupees", not "crores of rupees". Kurzon (talk) 16:38, 16 November 2024 (UTC)

What's the common usage in english? GoodDay (talk) 16:45, 16 November 2024 (UTC)

I don't think most people in the US understand what "crore" is, and would not recognize it as part of the English language. The online Merriam-Webster dictionary says it means ten million, specifically, a unit of value equal to ten million rupees or 100 lakhs. I think most people in the US would not even understand that a currency is being mentioned.

--Jc3s5h (talk) 17:00, 16 November 2024 (UTC)

Not just people in the US. Nobody outside of India can be expected to know what a crore is. Kurzon (talk) 17:15, 16 November 2024 (UTC)

We use meters over feet? Where?

In non-scientific articles with strong ties to the United States, the primary units are US customary (pounds, miles, feet, inches, etc.)

Aaron Liu (talk) 17:50, 16 November 2024 (UTC)

You get extra points for saying "US customary" and not "Imperial". 😉 Isaac Rabinovitch (talk) 18:20, 16 November 2024 (UTC)

imperial :3 Aaron Liu (talk) 18:30, 16 November 2024 (UTC)

I agree with Kurzon, do not use "crore", use "millions". Wikipedia is for a worldwide audience. Avi8tor (talk) 18:03, 16 November 2024 (UTC)

Kinda like how US units are used for US articles, I don't see the harm in using "crore", and it's way more work to manually convert to millions every time a member of India's vast diaspora in the Global North adds "crore" to an article, not knowing our ManualOfStyle. Aaron Liu (talk) 18:19, 16 November 2024 (UTC)

Except we don't favor meters over feet — we use both. That's what the Convert template is for.

Speaking as a non-Indian, who can never remember what how many is a "crore": I'm fine with it, as long as the international unit is also used. Isaac Rabinovitch (talk) 18:18, 16 November 2024 (UTC)

We already make an exception for feet. I see no good reason for barring a second exception. State in crore and convert to a unit non-Indians can understand (millions of rupees?). Dondervogel 2 (talk) 20:48, 16 November 2024 (UTC)

The article for the French movie Les Visiteurs lists the budget as "9.5 million", using a point as a decimal separator. In France they use commas for this, ie "9,5 million". We don't use the French notation convention for France-related articles. Kurzon (talk) 17:14, 16 November 2024 (UTC)

Is it the French style to use that notation in English? A different unit elicits way less confusion than a reversed decimal separator meaning anyways. Aaron Liu (talk) 17:50, 16 November 2024 (UTC)

Bad RFC; see WP:RFCNEUTRAL and the rest of the guidance there too. Unsurprisingly, this has just started out as a disorganized discussion that doesn't resemble a normal RFC...you might want to just remove the tag, get some feedback, and then start a proper one in a bit (separate subsections for discussion and survey are pretty helpful too). 35.139.154.158 (talk) 18:21, 16 November 2024 (UTC)
@Kurzon: I did advise you not to jump straight for a full-blown thirty-day formal RfC without first exhausting the suggestions at WP:RFCBEFORE. --Redrose64 🌹 (talk) 18:39, 16 November 2024 (UTC)

This RfC is clearly improperly formatted, Kurzon; thank you to our unregistered friend for pointing this out.

Oh come now. It seems to be developing nicely, I doubt that any editors are swayed by the wording. it's not perfect but perfect is the enemy of good and its good enough. Herostratus (talk) 04:47, 29 November 2024 (UTC)

That reply was before the appropriate discussion centers were notified and before discussion started to develop. It's not just formatting; it's that there was no prior discussion. Now we're effectively having both at the same time, especially when an informal discussion could've resulted in consensus without a time-consuming process. Aaron Liu (talk) 16:08, 29 November 2024 (UTC)

Consistency and clarity to our international readership are valid arguments in favor of prohibiting "crore" and "lakh". However, Aaron Liu makes good points about the fact that we allow local variation in articles with local ties, e.g. all of ENGVAR. I am unsure where I sit on this issue. I would like to see some Indian editors weigh in on this. Toadspike [Talk] 19:58, 16 November 2024 (UTC)

I also agree that crores are too obscure (as are lakhs), with use limited to South Asia. Feet and inches, while retrograde and infinitely useless, were used across most of the world not many generations ago. The major unit in Japanese is 万 (man), which is 10,000, but we do not use that because most people wouldn't know it. Engvar is somewhat different: we cannot avoid choosing between "colour" and "color", for instance, whereas we can easily write the globally recognized "millions" rather than crores. As for User:Aaron Liu's comment: if someone adds crore, it will be there until fixed – it's not pressing enough of a problem to hunt down every instance. Mr.choppers | ✎ 20:03, 16 November 2024 (UTC)

Good point about 万 – I completely forgot that Chinese has similarly different units. I think that settles it – either we allow crore and lakh alongside the East Asian 万 and 亿 (which I think is ridiculous) and an infinite variety of customary units, or we allow none.

(Two counterarguments: 1. This is a slippery slope argument, which is a logical fallacy. To which I say no, we can't give only one country special treatment, we ought to be fair. 2. The East Asian units are non-Latin characters and thus more impractical than "crore". This is true.) Toadspike [Talk] 20:15, 16 November 2024 (UTC)

On the subject of the myriad, I agree with Toads's second counterargument: there is no widely-recognized English translation for the unit in some "East Asian variant" of English; they just convert it to short scale in translations.

we cannot avoid choosing between "colour" and "color", for instance, whereas we can easily write the globally recognized "millions" rather than crores.

Part of my argument is that "crore" vs long scale is basically the same thing as "colour" vs "color": anonymous editors are going to add them. A ton. Expecting people to not use crore is like expecting people to not spell "colour". It's not pressing enough to hunt down, sure, but you're going to see sweet summer children adding crore into crore-free articles again and again and again. Aaron Liu (talk) 01:14, 17 November 2024 (UTC)

By the way, I've left a (neutrally-worded) note about this discussion at the Talk page of WikiProject India. Toadspike [Talk] 20:16, 16 November 2024 (UTC)

Don't allow crore. In the interest of making articles understandable to a wider audience, we already do this for the decimal marker (.) and separator for groups of 3 digits (,) as previously mentioned. We also require the use of short-scale even though long-scale hasn't entirely died out in the British Isles. Jc3s5h (talk) 21:16, 16 November 2024 (UTC)
The decimal marker and long/short scale have a much better reason for their ban: The symbols they use have very different meanings outside of their local context, while crore, lakh, etc. do not. Aaron Liu (talk) 01:04, 17 November 2024 (UTC)
Don't allow crore Per WP:COMMONALITY. This is not comparable with US v metric units where we report both - that is just a case of which is primarily reported. Furthermore, imperial units have a relatively recent historical usage across English. It is not like other issues of ENGVAR such as colour v color or ise v ize that do not affect understanding. For an international encyclopedia, using vocabulary common to all varieties of English is preferable - to the point of being paramount. Cinderella157 (talk) 22:38, 16 November 2024 (UTC)
Allow crore, lakh and Indian numbering system, but always, 1) link it on first use, 2) include what it is a measure of (rupees can not be assumed), 3) also include conventional numbering, and 4) allow it only in articles about the subcontinent. SchreiberBike | ⌨ 23:13, 16 November 2024 (UTC)
I agree with all of these conditions. While I remain somewhat ambivalent on the use of “crore” in general, we must provide enough context for non-Indian readers to understand them. Toadspike [Talk] 13:56, 17 November 2024 (UTC)
Allow crore, lakh per SchreiberBike, and with the same caveats. Dondervogel 2 (talk) 00:03, 17 November 2024 (UTC)
Allow ScreiberBike, per my comments above. Aaron Liu (talk) 01:20, 17 November 2024 (UTC)
Allow ScreiberBike. But see also Wikipedia:Manual of Style/India-related articles#Basic_India_conventions - "You may use the Indian numbering system of lakhs and crores but should give their equivalents in millions/billions in parentheses" — Preceding unsigned comment added by Asteramellus (talk • contribs) 00:30, 18 November 2024 (UTC)
Allow crore, lakh and Indian numbering system, but always, 1) link it upon first use in every section where it appears, 2) include what it is a measure of (rupees can not be assumed), 3) also include conventional numbering using template {{convert}}—i.e., don't convert yourself, and 4) allow it only in articles about the subcontinent. Mathglot (talk) 23:11, 18 November 2024 (UTC)
Hm; was very surprised to notice that the {{convert}} template does not currently support lakhs and crores. I think it should, and started a discussion about that. If you wish to comment, please go to Module talk:Convert#Indian numbering system: lakhs and crores. Thanks, Mathglot (talk) 23:50, 18 November 2024 (UTC)
The convert template converts units, like feet and metres. Crores and lakhs are not units, but multipliers. It would be like convert being used to convert between hundreds, thousands, millions etc. --Redrose64 🌹 (talk) 22:52, 19 November 2024 (UTC)
The {{lakh}} and {{crore}} templates make more sense than overloading {{convert}}. Stepho talk 23:02, 19 November 2024 (UTC)

I agree with SchreiberBike and others; "crores" and "lakhs" can always be used to add colour/color to an article as long as those requirements are met. Mr.choppers | ✎ 04:50, 20 November 2024 (UTC)
Do not allow. This is not the same as variations of English in wide use where there are multiple widespread usages (color or colour). While SchreiberBike's conditions for use are reasonable, I would say that the standard international measurements should always be primary and subcontinent-specific numbering as a secondary only in articles about the subcontinent. Avgeekamfot (talk) 09:50, 20 November 2024 (UTC)
What does "widespread" mean? Aaron Liu (talk) 12:17, 20 November 2024 (UTC)

Notified: Wikipedia talk:Manual of Style/India-related articles. jlwoodwa (talk) 01:04, 21 November 2024 (UTC)

Allow, but always ... exactly as Mathglot laid out above (other than, per Stepho-wrs and Redrose64, {{convert}} isn't actually the right template, or at least isn't presently). I would add a further caveat that these traditional Indic units (technically, multipliers) should be given secondarily not primarily, but I could live without that. — SMcCandlish ☏ ¢ 😼 11:55, 21 November 2024 (UTC)
Allow when appropriate, under conditions set out by ScreiberBike. Also, this RfC does not meet WP:RFCNEUTRAL. ThatIPEditor ^{Talk · Contribs} 02:18, 22 November 2024 (UTC)
Do not allow crore et al. It's not only native English-speakers who haven't a clue what it means when reading India-related articles; it's non-natives too. Tony (talk) 07:32, 22 November 2024 (UTC)
I don't get what native/non-native speakers have to do with the issue. Aaron Liu (talk) 12:21, 22 November 2024 (UTC)
Allow per ScreiberBike for South Asian articles. Johnbod (talk) 17:29, 22 November 2024 (UTC)
Allow All Indian academic/professional textbooks and all Indian reliable sources, with few exceptions for specific conditions, use lakhs/crores when denoting INR and millions/billions when denoting foreign currencies. Not allowing is not an option, unless editors want to disregard Indian readers. Using X million rupees is almost as uncommon in India as using Y lakh dollars. My suggestion -- for articles that use {{Use Indian English}} force editors to 1) link it on first use, 2) include what it is a measure of (rupees can not be assumed) with Indian comma separator at 00 after thousands and for articles that don't use that template force editors to always use millions/billions with 000 comma separator. — hako9 (talk) 03:01, 23 November 2024 (UTC)
Strongly disallow use of Indian comma separator. That would only serve to confuse. We don't permit a French comma separator on English Wikipedia. The Indian comma would be much worse. Dondervogel 2 (talk) 09:11, 23 November 2024 (UTC)

I concur entirely with Dongervogel_2 on this side-point; we cannot mix-and-match numeric separator styles. We've repeatedly had debates in the past about permitting "," instead of "." as a decimal point to suit the preference of some subset of readers, and the answer is always firmly "no", so this isn't going to be any different. I'm not a professional researcher in this area, but I have looked into the matter in the course of various style debates, and the evidence clearly shows Indian publications using "Western" number formatting systems (or whatever you want to call them) on a regular basis, though often alongside the Indic krore, etc., system. That is, it's just not plausible that English-using readers in/from India have any difficulty understanding our numeric material, especially after the rise of the Internet has exposed them to content from all over the world since the mid-1990s and pretty much ubiquitously since the early 2010 with the rise of mobile data. — SMcCandlish ☏ ¢ 😼 14:49, 24 November 2024 (UTC)
“it's just not plausible that English-using readers in/from India have any difficulty understanding our numeric material …” Of course the same could be said of American readers and the spelling of ‘colour’. — HTGS (talk) 17:41, 28 November 2024 (UTC)
What isn't the same is how many editors will add "colour" into articles while most wouldn't add numbers in the Indian system. Aaron Liu (talk) 18:30, 28 November 2024 (UTC)
I’m genuinely not sure what your point is? Editors are more likely to (erroneously) change spelling to ‘colour’, so that gives them more grounds for the MOS giving them parity with American English? I know we should be realistic about what we can control, but I don’t love that logic. — HTGS (talk) 03:18, 29 November 2024 (UTC)
Yes, that or add spelling that says "colour" is what I'm saying. Aaron Liu (talk) 04:03, 29 November 2024 (UTC)

Like I would campaign for navboxes to be placed in the "see also" section if it weren't so widespread and unduly investative to correct. The corrections for disallowing crore are the same thing to me. Aaron Liu (talk) 04:11, 29 November 2024 (UTC)

On this attempt at a colo[u]r false analogy: "What isn't the same" even more pertinently is that the cases aren't parallel in any way. Crore and lakh are not barely noticeable spelling differences of an everyday word used the same way in every single dialect of English; they're a radically different system of approaching large-ish numbers. There is no audience capable of reading en.wikipedia for whom either colour or color is impenetrable. If HTGS's pseudo-analogy is intended to suggest that ENGVAR should be undone on the same basis that we would rejecte or further restrain use of crore and lakh, that doesn't work since they're not actually analogous at all, plus the fact that not a single element of MoS is more dear to the community than ENGVAR; it is never, ever going away. If HTGS isn't actually suggesting we get rid of ENGVAR but is instead trying to suggest that opposition to crore is pretty much the same as advocating the death of ENGVAR, that's not cogent either, for the same false-analogy reason plus scoops of slippery slope, overgeneralization, and argument to emotion fallacies plopped on top. Aaron Liu's original "what isn't the same" point is that most editors will use color or colour as contextually appropriate in our content, yet very few will ever add lakh or crore to an Indic-connected article. That could be argued to be suggestive of a de facto community consensus already existing against those units' use at en.wikipedia. While it's worth considering, it's clouded by WP:SYSTEMICBIAS in that a comparatively small percentage of our editors are from India or its immediate environs, so the statistics are probably not usefully comparable even if they could be gathered with certainty. I would suggest that the reasons to rarely use crore/lakh and to always convert when used at all, has to do with end-reader comprehensibility, not with editor preference or usage rates. — SMcCandlish ☏ ¢ 😼 12:54, 23 December 2024 (UTC)

Because, the fact is, we aren’t using varieties of English solely to ensure accuracy or intelligibility. They are also being used to avoid recreating the Anglo-American hegemony that exists in published English, and to foster a connection in the community with the most interest in the subject. — HTGS (talk) 18:05, 28 November 2024 (UTC)
This is not MakeLocalsAsHappyAsPossiblePedia or EngageInCrossCulturalFeelGoodBackscratchingPedia or RightGreatWrongsPedia. It may be unfortunate in some sense that a "Western" (now globally internationalized) enumeration system dominates nearly everywhere (with arguably more benefits than costs), but it is a fact. And it has nothing to do with "Anglo-American" anything, being the same system used by the French and the Russians and the Japanese and so on, and predating both America and England and even the English language, going back to ancient Eurasia very broadly, from the Rome to China. (There's an incidental British correlation of course: it was largely the English, along with the Dutch, who pushed this system in India. That makes it socio-politically and emotively connected to India–UK and Indian–Western relations, but it is not an Anglic counting system and we are not to be confused by sentiment.) More to the point, the "job" of this site is to communicate clearly with as many English-competent readers as possible. The simple fact is that virtually no one outside of the Subcontinent and nearby islands (plus first-generation emigrées therefrom), think in or even understand lakh and crore; meanwhile pretty much everyone in India and thereabouts also understands millions, and hundreds of thousands, even if it is not their immediate mental model and they have to convert a bit in their heads, like Americans with metric units. There is no bothsides-ism to be had here; the sides are not equivalent. Finally, it is not the goal of our articles on Indic culture, history, geography, economics, etc., to appeal to and primarily serve the interests of people in South Asia, but everyone. For this reason, I'm supportive of retaining the permissibility of crore and lakh in relevant articles as long as they are always converted into the now globally prevalent enumeration system, and usually with that first unless there's an important contextual reason to use lakh/crore first. Best of both worlds: everyone gets to understand the material, and Indic numbering is not deleted. It's pretty much the same situation as American customary ("imperial") units of measurement: most of the world doesn't use or understand them, but we should not ban them, just always convert them to metric. (The only difference I can see is "wiki-political": our American editorial and read bases are so large that it would be very difficult to get consensus to always put American units second after metric even in articles about American subjects. That really should be the rule, but it'll be hard to get there.) — SMcCandlish ☏ ¢ 😼 12:54, 23 December 2024 (UTC)
Do not allow crore - I am not convinced that this word is actually English, and this is the English-language wikipedia. It seems that this is a foreign word that is used alongside English in areas that have ties to the language this word is from. Even in these areas, it seems that English speakers there fully understand what "millions", "thousands", etc mean, and there have been attestations linked above where they use both, presumably to help English speaking people understand what number is being referred to. My perspective here is colored by being an American expat living in Japan... in day-to-day speech, I will sometimes mix the languages and say "Oh, this costs 3 man yen." But I am under no circumstances thinking that "man" meaning "ten thousand" is English. I'm using another language's word. That's what it looks like they are doing here. Fieari (talk) 07:01, 28 November 2024 (UTC)
As an alternative, I would also accept allowing crore only if the "millions" number is included alongside it. Fieari (talk) 07:28, 28 November 2024 (UTC)

"Gumption" is borrowed from Scots; it is English. "Chutzpah" is borrowed from Yiddish; it is English. "Powwow" is borrowed from East-American indigenous language; it is English. "Crore" is borrowed from Hindustani; it is Indian English. All of the above are attested by dictionaries, while "man" to mean myriads is not. Aaron Liu (talk) 18:28, 28 November 2024 (UTC)
Allow crore - my gut feeling is to disallow it because it is not English as understood by the majority of English readers (including native speakers from UK/US/Australia/etc and second language speakers from China/S.America/Europe/etc). However, crore and lakh are words that Indians practically think in even when speaking English. We have a similar problem where an article is marked as British English and has 99 occurrences of "litre" - an American will still add new stuff with "liter" because it is so naturally to them. In the same way, we will be pushing it up hill trying to get them to stop. So, we should let them use it in articles related to the Indian region but never on anything outside that region. Each first usage should link to crore and lakh so that the few non-Indian region readers have a clue what's going on. I would not bother with conversion to millions - once you learn that they are just putting 0's at the end it becomes easy enough in a short time and conversions just clutter up the article. But do not allow grouping like 1,00,000 under any circumstances. Stepho talk 02:41, 29 November 2024 (UTC)
Don't allow crore. If there are people who don't know what "million" is, well some level of literacy is required here, yes. As to "link on first use", no, links are supposed to be "here's some extra/more detailed info about the subject if you want" not "you need to interrupt the flow of your reading and go off the page to understand this word". Herostratus (talk) 04:57, 29 November 2024 (UTC)
Actually that's exactly what links are for. Readers who know the general topic well can just read an article straight forwardly. But readers new to the general topic are likely to come across words they don't know yet and can follow the links to learn. Eg, in car articles we often talk about the camshaft. If you are new to the detailed study of cars then you can follow that link and then return later. Stepho talk 06:09, 29 November 2024 (UTC)

And if anybody thinks that a politely worded MOS rule will stop them adding crore and lakh then consider that at https://en.wikipedia.org/w/index.php?title=Nissan&diff=1256595427&oldid=1256557060 somebody added a MDY style date in spite of the article having 186 references in DMY style. I fix these (in both directions) practically daily. People do whatever comes natural and do not consider that any other way even exists.

But I do feel a little better after my vent :) Stepho talk 11:35, 29 November 2024 (UTC)
+1 and it’s worth reiterating that most advocates here are suggesting that the Indic value should always be “translated” into a Western value in parentheses, so most naïve readers would still be able to parse the article without following the link. — HTGS (talk) 06:21, 29 November 2024 (UTC)
Do not allow crore—India-related articles are for international readership. No one outside the subcontinent is familiar with crore. It is a disservice to readers to allow it. Tony (talk) 06:24, 29 November 2024 (UTC)
If they are not familiar with crore they can read the conversion to millions. And if they also want to learn about crore they can click on the link. I see no disservice. Dondervogel 2 (talk) 12:49, 29 November 2024 (UTC)

Perhaps some are not aware but English Wikipedia is heavily used in India. The Top 50 Report from 2023 had five items about Indian movies and movie stars. The latest week's most viewed Top 25 had 2024 Maharashtra Legislative Assembly election and Kanguva. According to Indian English there are 128 million English speakers there. If we say to basically never use crore and lakh, we are sending a discouraging, even insulting, message to many of our readers and editors. SchreiberBike | ⌨ 13:51, 29 November 2024 (UTC)
Allow in articles with strong ties to India, provided that the conversion is shown at first use. Hey, we could even write In non-scientific articles with strong ties to ~~the United States~~ India, the primary ~~units are US customary (pounds, miles, feet, inches, etc.)~~ multipliers are Crore and Lakh. See sauce for the goose. Also, it is very relevant that a huge fraction of en.wiki readers are Indian. "ccording to a 2011 census, 10.2% of the Indian population speaks English. This figure includes all Indians who speak English as a first, second, or third language. 10% of India's population is approximately 145 million people." Twice as many as in the UK, half as many as in the US. --𝕁𝕄𝔽 (talk) 11:49, 29 November 2024 (UTC)
Allow only with linking and conversion as per Mathglot. The most practical solution for both Indian and non-Indian readers. Chaotic Enby (talk · contribs) 23:41, 8 December 2024 (UTC)

Discussion

Maybe this can be solved technologically so that every user sees numbers in the way they are accustomed to? Alaexis_¿question? 20:43, 8 December 2024 (UTC)

This could be done for logged in users, but the vast majority of readers are not logged in with an account. Similar solutions have been proposed for date style and variety of English, but they won't work. SchreiberBike | ⌨ 20:50, 8 December 2024 (UTC)

The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

Four questions

Can 24-hour clock be used in articles with strong ties to United States (I have seen no US-related articles with 24-hour clock) such as: "The Super Bowl begins at 18:40 ET?
Can 12-hour clock be used with UTC time?
How are primary units of an article determined if the article has strong ties to both US and Canada, as Canada-related articles always use metric units first? For example, Great Lakes is such an article, and it currently uses imperial units first, but it would be more logical to use metric units first as a Canada-related article.
Why mixed units are not used with metric units? Why it is either 1.33 m or 133 cm, but never 1 m 33 cm? --40bus (talk) 23:04, 21 December 2024 (UTC)
I'd add a fifth question: why does Wikipedia not use ISO dates, i.e. yyyy/mm/dd? They are becoming more common internationally. Skeptic2 (talk) 00:02, 22 December 2024 (UTC)
I wouldn't recommend it.

Probably?

That should be decided on a case-by-case basis.

No benefit for the additional visual or semantic complexity; that's part of the appeal of the metric system, right?

English-language sources never use this format, and the English Wikipedia bases its style on that of other English-language media.
Remsense ‥ 论 00:58, 22 December 2024 (UTC)
You write "English-language sources never use this format", but this is untrue. ISO date format is widely used in scientific publishing and it is standard in aviation and for machine processing. Have a look at the Wikipedia entry List of date formats by country. You might be surprised.Skeptic2 (talk) 23:35, 22 December 2024 (UTC)
I personally use ISO format on my devices; if it helps, you can replace "never" with "almost never". Remsense ‥ 论 23:36, 22 December 2024 (UTC)

MOS:TIME says 12 and 24 clocks are equally valid. It's just that the majority of native English speakers use 12 hour clocks, so they choose to use 12 hour clocks. If you create an article (or are the first to mention times within an existing article) then you can choose. Don't change an existing article from one to the other. With the possible exception of US Army articles, you may get kick-back from readers not familiar with the MOS. See the WP:JUSTDONTLIKEIT essay.
UTC is an offset. It is a separate question from how you format that time. UTC can be used with either 12 or 24 hour clocks. See MOS:TIMEZONE but it doesn't actually say much.
Primary units are based on strong ties to a country. If you have multiple countries with a mix of units then you have multiple weak ties and no strong ties. Therefore we default to metric first, as per WP:UNITS. Only articles with strong ties to the US and UK get to use imperial units first.
A major benefit of metric is that we can change from m to cm to mm to km just by shifting the decimal point. Splitting it into 1 m 33 cm makes that harder and is now rarely used in metric countries. It was more common in my country of Australia during the first 20 years after metrication when we copied our old imperial habits but it fell out of favour and we now universally say 133 cm, 1.33 m or 1330 mm as appropriate. Countries using imperial units tend to use split units because it is so hard to convert miles to feet, gallons to ounces, etc in your head.
ISO 8601 dates are allowed in limited cases (mostly references and tables where space is limited). It is not used in prose because it is not yet common for native English speakers to use this in their day-to-day lives. Note that any other purely numeric format is strictly disallowed. See WP:DATEFORMAT Stepho talk 01:09, 22 December 2024 (UTC)
(In terms of accuracy in my own answers, 2 out of 5 ain't bad right?) Remsense ‥ 论 01:11, 22 December 2024 (UTC)

Being OCD helps 😉 Stepho talk 01:58, 22 December 2024 (UTC)

I'm unsure how to medicalize it, but I'm certainly obsessive and compulsive, and it only helps somewhat! Remsense ‥ 论 02:00, 22 December 2024 (UTC)

Answering #2 and #4 only

2. No. The clarity of UTC is obtained only with a 24-hour clock.
4. You could write 1 m + 33 cm if you want, but why make life so complicated? The plus sign is needed because without it a multiplication is implied (1 m 33 cm = 0.33 m²).

Dondervogel 2 (talk) 07:43, 22 December 2024 (UTC)

The answer to Q2 will depend at least in part on whether UTC was chosen because it's local time or because it's the international time standard. It would make no sense to allow the 12-hour clock for events in London between March and October, but ban it for events between October and March. Kahastok talk 14:56, 22 December 2024 (UTC)

@Kahastok: I don't get this reply. The time of an events in London is given according to BST (= UTC+01:00) in summer and according to GMT (= UTC+00:00) in winter – normally without either qualification stated unless it is the weekend when the time changes. It the time zone matters (for an internationally televised live event, for example), the time is normally given both ways: in the local and in the international notations. (Or did you not realise that GMT is just another timezone, not a synonym for UTC though often used that way, especially by seafarers.) 𝕁𝕄𝔽 (talk) 15:58, 22 December 2024 (UTC)

I don't accept that UTC is always distinct from GMT. Usually there is not enough information about the reasons a particular author used one or the other abbreviation to tell if the author intended a distinction or not. Jc3s5h (talk) 17:15, 22 December 2024 (UTC)

Well OK, if we're going to insist that the sub-second formal discrepancy between GMT and UTC is somehow vitally important (despite all evidence to the contrary) the split hairs do not count in the case of Lisbon, where the local time in the winter is defined as UTC, rather than just being UTC in practice. Why would we say that a winter event in Lisbon has to use the 24-hour clock, but a summer event does not?

For the record, I don't think I have ever seen a time recorded at 17:00 GMT (17:00 UTC) and I would like to see examples of that usage. Kahastok talk 19:48, 22 December 2024 (UTC)

and you never will, because it would be pedantic in the extreme. In fact most timestamps you see anywhere will be just one of (a) not stated, because it is for local use; (b) the local timezone (notation adjusted according to whether or not DST is in operation); (c) a poor third at "front of house" (excepting worldwide online systems like Wikipedia), UTC time. Use of both (b)&(c) at once is very rare, vanishingly so if b=GMT or even BST.

Jc3s5h is certainly correct for use of GMT in almost all sources pre this century and still quite a few recently – it will take 50 years to fall out of use as a world standard, I suspect. Perhaps more ... who would think that there are still people who insist on chain (unit)s?

Just to be clear, I am not proposing that we introduce an MOS rule mandating any notation. Just clarifying that GMT is not a synonym for UTC. 𝕁𝕄𝔽 (talk) 20:25, 22 December 2024 (UTC)

If you weren't aiming to be pedantic in the extreme, why bring it up? And in particular, why claim - specifically in the context of GMT vs UTC - that the time is normally given both ways: in the local and in the international notations in situations where time zone matters? 'Kahastok' talk 21:22, 22 December 2024 (UTC) s

My 2c:

Not just English speakers, anybody with an analogue wristwatch display does so. BUT (in the UK at least), train, bus and plane timetables are invariably shown using 24 hour clock notation. Basically, anywhere that it matters, where ambiguity might arise.
1. The application of am and pm to 12:00 noon and midnight seems to be a perennial source of dispute, see 12-hour clock#Confusion at noon and midnight. Good luck with writing an MOS guidance that avoids that minefield.
I was about to declare that UTC offsets never exceeds 12:00 so crisis, what crisis? But I think there is a UTC+13:00 on one of the Pacific islands near the date line?
Stepho, the use of imperial units in the UK is dying out, literally as well as metaphorically since they are preferred by the older generation. Don't be fooled by the rail-fans insistence on chains – all UK railway engineering has been done in metric since 1975. So no, MOS:RETAIN applies to UK articles too. Except articles under the aegis of Wikipedia:WikiProject UK Railways, of course. --𝕁𝕄𝔽 (talk) 15:43, 22 December 2024 (UTC)
I concur with Stepho's reply.
Anybody who puts their boiled egg upside down should be taken out and beheaded immediately! (aka, ask us again in a 100 years time but it is a non-starter right now.)

Here endeth the lesson. 𝕁𝕄𝔽 (talk) 15:40, 22 December 2024 (UTC)

You say, the use of imperial units in the UK is dying out. Is it therefore your contention that the British (or even just younger British people) all use kilometres really and just put miles on all the road signs to confuse foreigners? Kahastok talk 19:48, 22 December 2024 (UTC)

Because of the multitude of road signs and therefore the huge cost of moving from miles, that one will likely never change. In most other fields, however, there has been a progressive move toward using metric measurements in the UK over recent decades. MapReader (talk) 04:05, 23 December 2024 (UTC)

Never mind that other countries that went metric changed our road signs just fine. Stepho talk 05:09, 23 December 2024 (UTC)

Dondervogel 2

, why must UTC be 24 hours? UTC is just a timezone. Technically it is no different any other timezone and the other time zones can use either 12 or 24 hour times as they wish. Of course, UTC is a little special in that it gets used as the "universal" timezone. And when somebody wants to be unambiguous they tend to use 24 hour time. And when they want to be really unambiguous they write it as UTC rather than local. But a lot of that is just convention. They could equally well say 4:00 pm UTC and still be very precise and unambiguous.

Also, why do you need the "+". In the 1970s in Australia (just after metrication) we used to see "1 m 33 cm" a lot. I've never seen anyone think that it was multiplication. It was more likely from the habit of doing "4 ft 7 in". Once we learnt that writing it as 1.33 m or 133 cm made conversion between them trivial (just shift the little dot), we dropped the complication of mixed units. Stepho talk 05:09, 23 December 2024 (UTC)

UTC is not a time zone. It's a time standard, and it uses a 24-hour clock.
In the language of the SI, symbols have special meanings. If you mean addition (as here) you need a "+" sign. In the absence of any other symbol, a space denotes multiplication. Outside the SI you can invent any conventions you want, and Wikipedia sometimes chooses to depart from the SI, via MOSNUM. I don't believe MOSNUM permits this particular departure.

Dondervogel 2 (talk) 08:30, 23 December 2024 (UTC)

Remsense, one reason Wikipedia can't rely on ISO 8601 throughout is that some articles express dates in the Julian calendar, or even the Roman calendar, and ISO 8601 only allows the Gregorian calendar. ISO 8601 is fine for airline schedules and hotel reservations, but it truly sucks for history. Jc3s5h (talk) 15:13, 22 December 2024 (UTC)

If we can't get Americans to switch to DMY, or Brits to switch to MDY, what hope do we have of getting both groups to switch to YMD? --Redrose64 🌹 (talk) 00:03, 23 December 2024 (UTC)

I think the biggest problem with YMD, besides unfamiliarity, is that you frequently want to suppress the Y part when it's understood, and that's harder to do when it's at the start. --Trovatore (talk) 00:14, 23 December 2024 (UTC)

I think the UN should enforce use of DMY worldwide on Mondays, Wednesdays and Fridays, MDY on Tuesdays and Thursdays, and of course dedicate the weekends to YMD. Remsense ‥ 论 00:20, 23 December 2024 (UTC)

Whaaaaat? Why would we want the least fun format on the weekend? — SMcCandlish ☏ ¢ 😼 09:02, 23 December 2024 (UTC)

Year-first encourages us to meditate on the long term while many are less occupied at work. Remsense ‥ 论 08:59, 24 December 2024 (UTC)

My responses to these questions would be:

There is no strong tie of "18:40" format to the US, or the UK, or whatever. It's a format used in a variety of military, otherwise-governmental (e.g. transport/transit scheduling), and sometimes scientific and a few other contexts, and that's true inside and outside the US. It's a completely abnormal format outside of those kinds of contexts, and people don't use it on an everyday basis (that I know of; maybe there is some English-using country in which it has been so aggressively imposed that it's become an everyday norm there and people don't know what "3 pm" means any more, but I'm not aware of such a place). MOS:NUM grudgingly permits its use, but 24-hour format verges on "user-hateful" and should be avoided in most circumstances (i.e. where it's not an established norm for the subject in question).
- On JMF's side point about "12:00 pm", MoS could easily have a rule about this, just to settle the confusion, which is common among the general populace, but not among reliable sources on time and writing, in which it virtually always corresponds to "12:00" in 24-hour time, with "12:00 am" being "00:00". MoS saying something about it, though, should be to avoid it in favor of "midnight" and "noon", because confusion among everyday people persists. (My city is gradually changing all of its "No Parking 12 AM – 6 AM, Street Cleaning, Tu, Th" signs to "No Parking 12:01 AM – 6:01 AM, Street Cleaning, Tu, Th" because of this factor).
Meaningless, confused question. As Stepho-wrs explained, UTC is an offset, not a format. There's a standardized way of writing the name of a UTC time-zone offset, e.g. as "UTC+05:00", but that's not relevant to how times are used or referred to (in various styles) for typical human consumption. Likewise, the Unicode name of "@" is "U+0040 @ COMMERCIAL AT", but this has no implications for use of the symbol or for plain-English references to it; writing "the at-sign" is not an error. When WP puts "3:05 pm, February 3, 2002 (UTC)" in someone's sig to conform to their date settings in the WP "Preferences" panes, that is also not an error.
- Stepho-wrs (which surprises me, given the above) wondered why UTC offset names use a +. It's because the offsets run both directions, e.g. "UTC−05:00" is US and Canadian eastern standard time, and rendering the positive ones as "UTC 05:00" or "UTC05:00" would be problematic for humans and automation alike in various ways. The + isn't any more superfluous than the leading 0 on 00–09.
A Canada–US squabble over ordering: A) Who cares? We have {{convert}} for a reason. B) This is a pretty good argument (from Stepho-wrs): "If you have multiple countries with a mix of units then you have multiple weak ties and no strong ties. Therefore we default to metric first, as per WP:UNITS." B) If that argument were not persuasive, then MOS:STYLEVAR still already covers this: When there are two competing acceptable styles, do not change from one to the other without an objectively defensible reason. Try to establish consensus on the article's talk page about which should be preferred, if you are convinced a change should happen. Iff such a consensus cannot be reached, then default to whatever was used in the first post-stub version of the article (same as with ENGVAR disputes, and CITEVAR ones). So, we are not missing any rules.
It's "1.33 m" (not "1 m 33 cm") primarily because that is how the metric system is internationally standardized and how it is used in the real world, rather consistently. The two-units version is also less concise, and annoyingly repetitive because of how the units are named. And the system is designed to be decimal from the ground up. Thus Steoph-wrs observation: "Once we learnt that writing it as 1.33 m or 133 cm made conversion between them trivial (just shift the little dot), we dropped the complication of mixed units." It's not WP's role to treat occasionally-attestable but very disused variants away from a near universal system as if they had become norms and must at all costs be permitted. (Much of MoS's role is eliminating unhelpful variation that is confusion or which causes cyclic dispute, even if we settle on something arbitrary; but most of MOS:NUM is not arbitrary but standards-based.) As for US customary (or "imperial" units, never mind the British empire doesn't exist any longer and what's left of it metricated a long time ago), you can find decimal uses of it for various purposes in real-world publications (e.g. "0.35 in"), but it tends to be for special purposes, like establishing margin widths when printing on non-metric paper, and in electronic media when calculation or sorting might be needed. But the typical use of such units is in "3 ft 7 in" form because they are unrelated units, and because the two-unit split format is deeply conventionalized, including in various industries like construction. That's not true of "3 m 7 cm".
- I don't buy Dondervogel_2's "multiplication implied" argument. Virtually no one outside of some particular ivory towers (and even then only in specialist material that was explicit about it) would ever interpret any "# unit1 # unit2" construction, in any context, as a multiplication operation. The real world routinely uses formats like this and never means multiplication by it. E.g. look at the fine print on any laptop's or other device's power-brick; you'll likely see back-to-back, undivided measurement-and-unit-symbol pairs, like "12 W 3.7 A".
Skeptic2's add-on ISO-dates question: WP doesn't use 2024-12-23 format (except for special purposes) because it is not a norm, anywhere (as an ENGVAR or other geographical or dialect consideration). It's only standardized within specific industries, systems, processes, organizations, and other specialized usage spheres. (I use it very, very frequently in web development and other coding. But it's not something I'd use in a letter or a novel or an op-ed, because it's a format for computers, and for precision and cross-language exchange among engineers and scientists, not a format for everyday communication.) I've never seen one iota of evidence of broad and increasing acceptance of ISO among the general public for daily use, in regular writing (though ability to parse it has likely increased in the last 30 years because of the Internet and the amount of people's exposure to code that uses it). But it does not match anyone but maybe an ultra-nerd's English-language parsing. If you're American, probably (unless you are older and rural) what you think and say aloud to express today's date is "December 23, 2024" or perhaps "December 23rd, 2024". If you're not American, you probably (some Canadians are an exception too) would express it as some variant of "23 December 2024", "23rd December, 2024", or "the 23rd of December, 2024", depending on your age, social background, country of origin, etc. (American yokels often use the last of those; I have relatives in the Deep South who do it habitually.) These correspond closely (between exactly and too-close-to-matter) to MOS:DATE's two "M D, YYYY and "D M YYYY" formats. An ISO date does not. It's very unnatural. It requires the reader (most readers, anyway) to stop and "translate" it in their heads, thinking about which block of numbers means what, and so on. (I've been using ISO dates on a daily basis since around 1990, and I still have to think about it a little, and once in a while get it wrong, especially shortly after transferring from narrative work to coding work.) Worse, many people do not know at all whether that represents YYYY-MM-DD or YYYY-DD-MM; lots of non-geeky non-Americans mistakenly think it's the latter because they are used to D M YYYY order otherwise, and the idea of the month coming before the day is foreign to them, an annoying Americanism. I run into this problem in a great deal of online content.

— SMcCandlish ☏ ¢ 😼 09:02, 23 December 2024 (UTC)

Official documents in South Africa are YYYY-MM-DD, I personally use it to name bank statements etc. on my computer because they are easier to find. It depends on what you are used to. Avi8tor (talk) 12:56, 29 December 2024 (UTC)

It isn’t however very readable, on articles of prose. MapReader (talk) 18:20, 29 December 2024 (UTC)

To reiterate a distinction that's not potentially reducible to cultural acclimation, it's clear that purely numerical formats are less natural in prose. Remsense ‥ 论 18:23, 29 December 2024 (UTC)

Mixed spelled/figure format

How did we come to this guidance?

Comparable values near one another should be all spelled out or all in figures, even if one of the numbers would normally be written differently: patients' ages were five, seven, and thirty-two or ages were 5, 7, and 32, but not ages were five, seven, and 32.

This goes against the AP Stylebook that pretty firmly enforce that the numbers nine and below should be spelled out, while figures should be used for 10 and above. I’m not as aware as other style guides, is this a case of AP being the odd one out… or is Wikipedia style the odd one? -- RickyCourtney (talk) 04:14, 28 December 2024 (UTC)

The example shows it very well. Mixing both types in one sentence like ages were five, seven, and 32 looks very amateurish. Stepho talk 05:43, 28 December 2024 (UTC)

I agree, but as the MoS is the only style guide I've perused at length, I'd naturally be inclined to. I wonder what the provenance of this guideline is also—and that of other guidelines of note as well if anyone knows and cares to waste time telling me. Remsense ‥ 论 05:54, 28 December 2024 (UTC)

Saying it “looks very amateurish” is very much a subjective opinion.

But to focus this on my more real-world concerns, this question was prompted by in connection to coverage of the jet crash in Kazakhstan. So in keeping with that, I present how the New York Times handles three such sentences on one article on the topic: Kazakhstan’s Emergency Situations Ministry said that at least 29 people had survived, including two children … Kazakhstan’s transportation ministry said that the flight’s passengers included 37 Azerbaijani nationals, 16 Russians, six Kazakh citizens and three Kyrgyz nationals. … The airline’s last major episode was in 2005, when an An-140 plane crashed shortly after takeoff, killing 18 passengers and five crew members.

Because of editors closely following our current MOS, our introduction on this same topic reads: On 25 December 2024, the Embraer 190AR operating the route crashed near Aktau International Airport, Kazakhstan, with sixty-two passengers and five crew on board. Of the sixty-seven people on board, thirty-eight died in the crash, including both of the pilots and one flight attendant, while twenty-nine people survived with injuries.

If we adopted AP style it would read: On 25 December 2024, the Embraer 190AR operating the route crashed near Aktau International Airport, Kazakhstan, with 62 passengers and five crew on board. Of the 67 people on board, 38 died in the crash, including both of the pilots and one flight attendant, while 29 people survived with injuries.

In my opinion, the AP style is vastly superior to what is suggested by our current MOS. RickyCourtney (talk) 07:29, 28 December 2024 (UTC)

The present guidance not to mix forms has consensus here. If you want that to change you'll need to propose a change to the wording, and explain why it is better. Saying "AP does it that way" seems unlikely to change the consensus. Dondervogel 2 (talk) 07:40, 28 December 2024 (UTC)

Long time editor, but this is definitely the first time I’ve encountered a MOS rule that I found so out of line with how I am used to writing (as you can probably surmise, I use AP in my day job). Frankly, I was just trying to get insight into why this was the consensus. I’m happy to propose something, is this the correct venue? Does it need to be in a formal format? RickyCourtney (talk) 08:17, 28 December 2024 (UTC)

Go ahead and suggest an improvement. This is the right place for it. Indeed it is the raison d'etre of this talk page. There is no formal format. Just make sure the proposed change is clear, and explain how it results in an improvement. Dondervogel 2 (talk) 08:21, 28 December 2024 (UTC)

It's pretty clear they're suggesting the AP style, right? I don't think it'll catch on here, though. However, one point in its favor one could argue is it doesn't depend at all on the surrounding context. Remsense ‥ 论 08:24, 28 December 2024 (UTC)

I agree the verbatim AP wording, including “You should use figures for 10 or above and whenever preceding a unit of measure or referring to ages of people, animals, events or things”, would be unlikely to gain acceptance here, mainly because of its far-reaching consequences for other parts of MOSNUM. Let’s judge the proposal when it comes. Dondervogel 2 (talk) 08:50, 28 December 2024 (UTC)

No one has yet replied to the "why?" question. One would need to check the archives to be sure, but I imagine one reason is to avoid bizarre combinations like "the sum of 11 and two is 13". Dondervogel 2 (talk) 09:18, 28 December 2024 (UTC)

I suspect a significant part of the answer to “why?” is that, unlike other publications that set down a preferred style which they then use universally, Wikipedia explicitly tolerates a variety of styles across its ‘publications’ - most obviously for the national varieties of English, and date formats, but also in many other respects (‘AD’ or ‘CE’ being just one example) - with the MoS itself being guidelines that are widely respected, but not policy that can be rigidly enforced. This is a pragmatic compromise, given our global reach and multitude of editors of all ages and nationalities, and the practical impossibility of enforcing any single way of writing. But it does make consistency a policy issue for WP, which it simply isn’t for any other publisher (since by definition their style guides ensure that everything is consistent). Thus WP guidelines put a lot of emphasis on style choices being internally consistent within articles, because they aren’t between articles. When it comes to number format this means using either words or figures, but not a confusing jumble of both. Personally, I think this is a sensible guideline and would expect to oppose any proposed change, unless the argumentation is exceptionally convincing. MapReader (talk) 14:08, 28 December 2024 (UTC)

I'd say that Of the 67 people on board, 38 died in the crash, including both of the pilots and one flight attendant, while 29 people survived with injuries is absolutely fine and in agreement with our guidelines. The numbers one and 29 are so far from each other that there's just no reason to consider them "comparable" (except in the trivial sense that you can compare anything with anything, but that's certainly not the intended one here). I'd also consider with 62 passengers and five crew on board as fine since crew members and passenger numbers aren't really comparable either – there'll likely to be an order of magnitude or more away from each other, as in this case. That's very different from people's ages (the example given), which all come from a population's age distribution and rarely exceed 100. Gawaon (talk) 08:49, 28 December 2024 (UTC)

I would argue the present guidance should result in "62 passengers and 5 crew", not "62 passengers and five crew". I have the impression RickyCourtney would like to change the guidance to reverse that preference. Dondervogel 2 (talk) 08:58, 28 December 2024 (UTC)

62 passengers and 5 crew is certainly possible if we consider this as falling under the guideline. However, Of the 67 people on board, 38 died in the crash, including both of the pilots and 1 flight attendant, while 29 people survived with injuries is certainly too odd to consider! My point, of course, was that these sentences don't fall under the guideline anyway, due to these numbers not really being "comparable". Gawaon (talk) 09:39, 28 December 2024 (UTC)

Re: 'Saying it “looks very amateurish” is very much a subjective opinion.' Sure. But your follow up of "in my opinion" is also subjective. There are no objective measurements here. The alternatives are:

Existing MOS: "with 62 passengers and 5 crew on board" or the equally allowed "with sixty two passengers and five crew on board". Both are consistent and do not require me to do a mental switch between styles. I like the all numbers version and hate the all words version - subjectively of course ;) The disadvantage is that it disagrees with a couple of major US style guides - which WP is not required to match anyway.
AP/Times style: "with 62 passengers and five crew on board" Advantage is that it is the same as a couple of major style guides used in the US. Do British style guides agree? Disadvantage is it requires that mental switch halfway through the sentence.

It is entirely subjective whether the mental switch or matching an outside style guide is more important to you. If you like consistency (like me) then consistency is more important. And naturally, if you grew up in the US then matching major US style guides is possibly important.

Re: 'The numbers one and 29 are so far from each other that there's just no reason to consider them "comparable"'. They are in the same sentence and are comparing similar things (people). Why would you consider crew and passengers as different when listing fatalities?

Re: 'Of the 67 people on board, 38 died in the crash, including both of the pilots and 1 flight attendant, while 29 people survived with injuries certainly too odd to consider.' Why too odd? Its the form that I personally prefer and allowed by the current MOS. Stepho talk 13:09, 28 December 2024 (UTC)

29 only has meaning to me in that it is comparable to 1. Remsense ‥ 论 13:15, 28 December 2024 (UTC)

This isn’t just “US style.” AP is US-based, but they serve news organizations across the world. Reuters, which is UK-based, uses the same style in this article. As does Euronews. As does the Irish Mirror. RickyCourtney (talk) 15:40, 28 December 2024 (UTC)

Fair enough - not just US. But still an external style that is just one among many and one that we are not necessarily compelled to match. Stepho talk 22:44, 28 December 2024 (UTC)

@Gawaon this is an extremely helpful interpretation. Thank you. I wonder if you and others would weigh in on another sentence in the Azerbaijan Airlines Flight 8243 article: The aircraft was carrying sixty-two passengers. Of those, thirty-seven people were citizens of Azerbaijan, sixteen of Russia, six of Kazakhstan, and three of Kyrgyzstan. Four minors were on board. My preferred way to rewrite this would be: The aircraft was carrying 62 passengers. Of those, 37 people were citizens of Azerbaijan, 16 of Russia, six of Kazakhstan, and three of Kyrgyzstan. Four minors were on board. That would be in alignment with how it’s been written in the New York Times, Euronews and the Irish Mirror. -- RickyCourtney (talk) 15:58, 28 December 2024 (UTC)

But is more readable as it was. MapReader (talk) 18:01, 28 December 2024 (UTC)

My choice would be all numeric: The aircraft was carrying 62 passengers. Of those, 37 people were citizens of Azerbaijan, 16 of Russia, six of Kazakhstan, and 3 of Kyrgyzstan. 4 minors were on board. No mental context switch required between numeric and spelt out words within closely related sentences — which could easily be a combined: The aircraft was carrying 62 passengers. Of those, 37 people were citizens of Azerbaijan, 16 of Russia, six of Kazakhstan, and 3 of Kyrgyzstan — 4 minors were on board. Stepho talk 22:44, 28 December 2024 (UTC)

+1 to this, though I admit my preference is biased because I've been taught in business correspondence to write related numbers either in words or figures, with figures taking precedence if the largest number is at least 10. —Tenryuu 🐲 ( 💬 • 📝 ) 04:20, 2 January 2025 (UTC)

Okay, so I did some more research this morning and found the answer I was looking for. This is a case of journalists adopting a style different from academics, and the MOS adopting the academic style. The APA has strict rules about consistency within categories, requiring numerals for all items in a list if any number is 10 or above. But it appears our MOS most closely matches the Chicago Manual of Style, which requires consistency, but allows for context-specific judgment if numerals or spelled-out numbers are used. -- RickyCourtney (talk) 20:46, 28 December 2024 (UTC)

Acceptable Date Format: Month Year

Right now, "Month Year" is listed as an acceptable format, with an example of September 2001, but this is *bad grammar*, violating the basic rules of English. There are two acceptable ways to convey this, grammatically:

Month of Year (September of 2001), which is listed as unacceptable but is correct grammar in the form Noun of Noun, e.g. Juan Esposito of Peru.
Month, Year (September, 2001), also listed as unacceptable, but again, correct grammar, of the same shape as general dates (September 1, 2001), which *is* listed as acceptable, which is correct but inconsistent, because September, 2001 and September 1, 2001 are two uses of the *same format and grammar*.

"September 2001" is bad grammar and an unacceptable format and should be labeled as such. Quindraco (talk) 15:48, 30 December 2024 (UTC)

It’s common English usage, both in the UK and US, so on what authority are you suggesting it is bad grammar? MapReader (talk) 15:51, 30 December 2024 (UTC)
Agree with MapReader, this is standard. Giant Snowman 15:55, 30 December 2024 (UTC)
Agree with MapReader. Chicago Manual of Style 18th ed. ¶ 6.41 states "Commas are also unnecessary where only a month and year are given...." and gives the example "Her license expires sometime in April 2027." Jc3s5h (talk) 16:30, 30 December 2024 (UTC)
There ain't nothin' wrong with September 2001. Dondervogel 2 (talk) 20:07, 30 December 2024 (UTC)
To be clear, that particular month was not one of unalloyed pleasantness, but the formatting has nothing wrong, anyway. E Eng 21:51, 30 December 2024 (UTC)
@Quindraco: You're about twenty years too late to change the guideline. --Redrose64 🦌 (talk) 21:25, 30 December 2024 (UTC)
Ah, yes. The very well-respected defense of "we've been doing it the wrong way for so long, lord knows we mustn't stop now." Quindraco (talk) 05:27, 7 January 2025 (UTC)
Except you haven't shown it to be wrong in the first place. "Month Year" dates have always been taught to be correct in my experience. If you think about it, requiring "July, 1776" would also require "4 July, 1776". I have noticed that my computer's available date formats include a few oddities that I was always taught were flat out wrong. Is that where you are getting this idea?--User:Khajidha (talk) (contributions) 00:28, 9 January 2025 (UTC)
Yep. Just checked. Windows has "Wednesday, 5 April, 2017" and "5 April, 2017" listed as date formats. Commas should only be used within the date when it is not in either "day-month-year" or "year-month-day" order. I've sent feedback about this, but I doubt that anything will be done about it.--User:Khajidha (talk) (contributions) 16:55, 9 January 2025 (UTC)
The OP's complaint is, I regret to say, just so much WP:MISSSNODGRASSism. E Eng 21:52, 30 December 2024 (UTC)
Agree with MapReader. "September 2001" is perfectly acceptable in formal written English and was acceptable long before I was born. --Coolcaesar (talk) 06:38, 7 January 2025 (UTC)
It's recognised to be standard usage in Canada. —Tenryuu 🐲 ( 💬 • 📝 ) 16:12, 7 January 2025 (UTC)
"January 2018" is the official usage in Australia: https://www.stylemanual.gov.au/grammar-punctuation-and-conventions/numbers-and-measurements/dates-and-time ("Incomplete dates" section). Stepho talk 00:50, 9 January 2025 (UTC)
Agree with those above; "September 2001" is perfectly acceptable. Peter coxhead (talk) 15:02, 9 January 2025 (UTC)

Weekdays

Does the manual of style say anything about including weekdays next to dates e.g. "Wednesday 1 January 2025"? I couldn't find it anywhere in the MOS. I don't see it often so I assume the answer is that the weekday should not be there (unless it's important for some reason). But if it's not in the manual of style somewhere (I'm sure it is) then we might want to add it. ―Panamitsu (talk) 08:12, 23 January 2025 (UTC)

I haven't checked the MOS (and it might not be in MOSNUM because the day of the week is neither a number or part of the date), but my recollection is that the day of the week is mentioned when relevant (say if a notable event happened in a church, during Sunday mass), and not otherwise. Dondervogel 2 (talk) 10:01, 23 January 2025 (UTC)

MOS:CENTURY appears to be incorrect

I'm surprised that this hasn't been fixed already but MOS:CENTURY currently incorrectly claims that "the 17th century as 1601–1700", for example. I was about to fix the 21st century article which incorrectly claims that the 21st century started in 2001, not 2000, but then noticed that it's only like that thanks to this MoS guideline!

There have been quite a few news articles analysing the 21st century recently, many of them because the first quarter of the century (2000-2024) is now over: Guardian, Bloomberg, Billboard, IFIMES, New York Times.

I can only assume the current MOS wording came out of the mistaken assumption/hypercorrection that a century must begin in a year ending in "1" thanks to the lack of a year zero in the calendar system, but that is of course not how the term is actually used in any sources. Thoughts on the best way of fixing this? I imagine quite a few articles will be affected by this error given it's somehow ended up in the MOS. Chessrat ^{(talk, contributions)} 13:29, 1 January 2025 (UTC)

If it ain't broke, don't fix it. MOS:CENTURY is correct. Ask yourself when the 1st century CE (using the proleptic Gregorian calendar ) began and then work your way forward. -- Shmuel (Seymour J.) Metz Username:Chatul (talk) 15:22, 1 January 2025 (UTC)
But there wasn’t such. The dating system was invented many years later (and incorrectly, as it turned out) and applied retrospectively. Such that it doesn’t matter whether there was a year zero, or not. Centuries nowadays are commonly recognised as 1900-1999, 2000-2099, and it’s only the WP pedants that hold out for 1901-2000. MapReader (talk) 17:55, 2 January 2025 (UTC)
Where did you hear that. I was taught for 60 years it was 1901-2000. Did schools change their courses recently? I guess it wouldn't be the first time, but this sounds like since so many get it wrong we should make sure that Wikipedia follows that same wrong thinking. Like people following a printing error on the term "Blue Moon" so they think it's the second full moon of a month. Fyunck(click) (talk) 09:38, 3 January 2025 (UTC)
That sounds like a case of Lies Miss Snodgrass told you. (I'm not saying it's actually a lie, but it's a lie that that's the only way in which centuries can be spliced.) Gawaon (talk) 11:01, 3 January 2025 (UTC)
Chessrat didn't explain where they looked for sources to justify the assertion "but that is of course not how the term is actually used in any sources." Wikipedia guidelines do not need to cite sources, since they announce the community's consensus on various matters. It is articles that must cite sources. A number of sources are cited at "Century" including

"century". Oxford Dictionaries. Archived from the original on December 30, 2019. Retrieved 20 January 2021.

Jc3s5h (talk) 15:43, 1 January 2025 (UTC)

“Incorrect” is not the way I would put it. Either you treat it as a style decision, with both systems being valid ways to designate the years (using either 1–99 or 1–100 for the first century) or you treat it as a logical / mathematical system, ending at 100 because you want every century to actually be 100 years, and the first year wasn’t 0. I could see it either way, but I don’t see a lot of sense trying to change it now.

What might be more sensible to pursue is a footnote that acknowledges and explains the two common ways of counting. — HTGS (talk) 03:28, 2 January 2025 (UTC)

+1 E Eng 04:27, 2 January 2025 (UTC)

I don't think there's any evidence that there are two different common ways of counting? As far as I can tell from looking into this, use of the term for the period beginning in a year ending in "1" is very rare, and the only sources that mention the "ending in 1" definition (such as the Oxford dictionary entry mentioned by @Jc3s5h: mention that it is a technical definition only and not used that way in practice. It is not the case that there were widespread celebrations of the new millennium both on 1 January 2000 and also 1 January 2001!

If there were two equally-used systems then I would agree with your comment, but that isn't the case; Wikipedia has a duty to provide accurate information even if it does take a significant amount of work fixing this across various articles. Chessrat ^{(talk, contributions)} 16:15, 2 January 2025 (UTC)

How many years were there in the 1st century? Dondervogel 2 (talk) 18:27, 2 January 2025 (UTC)

100, obvs. 1 AD to 100 AD. Next question please? --Redrose64 🦌 (talk) 21:12, 2 January 2025 (UTC)

My question was in response to Chessrat's post claiming that centuries start in 00, in which case they must end in 99. If the 1st century had 100 years, its first year would therefore have been 1 BC (and the 1st century BC would have ended in 2 BC). Alternatively, if the first year of the first century was 1 AD, it would have been a century with 99 years. Just trying to understand how it works (I don't know which of the two is more bizarre). Dondervogel 2 (talk) 21:44, 2 January 2025 (UTC)

It is a matter of personal preference. I find it logical and satisfying that the 19th century ended with 1900 and the 20th century ended with 2000. There are many people, though, who are more comfortable with the 19th century consisting only of the years that began with 18-- and the 20th century consisting only of the years that began with 19--. I remember that Stephen Jay Gould, someone I have long admired for his adherence to logic, stated that he was willing to accept that the First century consisted of only 99 years (although I think he was wrong). We do need to be consistent in Wikipedia, however, and if anyone feels strongly enough about the current guidance being wrong, RfC is thataway. Donald Albury 22:10, 2 January 2025 (UTC)

Again, the numbering of years AD/BC wasnt actually devised until over five centuries after the purported BC to AD break point, and such numbering was not widely used until over eight hundred years afterwards. And it was then applied retrospectively to historical events (with, historians now believe, an error of four years in terms of when they were trying to pitch the start), relatively few of which during that period can be fixed to a particular year in any case (not insignificantly because when these events were recorded, the AD/BC calendar system didn’t exist). So it’s an artificial construct and it doesn’t really matter what the first year was purported to have been. MapReader (talk) 22:24, 2 January 2025 (UTC)

Sources are fairly clear that in common usage, a century starts with a year ending in –00, so yes, by implication that means that the 1st century had 99 years (albeit of course the Gregorian calendar did not enter use until far later so this is purely retroactive)

I didn't really expect that there would be any disagreement with this– will probably start an RfC to gain wider input as it seems like this will be a matter which there is somehow internal disagreement on. Chessrat ^{(talk, contributions)} 22:38, 2 January 2025 (UTC)

Why should all centuries have the same length? Years haven't always the same length, so why should centuries be any different? Gawaon (talk) 08:08, 3 January 2025 (UTC)

@Chessrat and Gawaon: A century doesn't have to be 100 years, but it must be 100 somethings, for example 100 runs in a cricket innings, or a military unit comprising 100 Roman legionaries. This is because the word "century" is derived from "centum", which is Latin for "hundred". If you had a span of 99 years, it couldn't be called a century. Also from "centum" we get words like "cent" for the hundredth part of a dollar. If I gave you 99 cents, you probably wouldn't give me a dollar in exchange. By contrast, the word "year" doesn't have a comparable derivation from 365 (or 366). --Redrose64 🦌 (talk) 22:24, 3 January 2025 (UTC)

Common usage having the 21st century starting in 2000 is utterly irrelevant to the Latin etymology of the word "century". The calendar system came into use long after 1 CE so analysis of the durations of past centuries is purely retroactive and simply a case of how society largely agrees to define it.

If one were to strictly assume Latin etymology is always fully indicative of how a word is used, then the article on September would say that it is the seventh, not the ninth, month of the year. Chessrat ^{(talk, contributions)} 07:40, 4 January 2025 (UTC)

Yes, the argument by name origin is fairly weak, since actual meanings don't always live up to their origins – or certainly not exactly. Centurion say: "The size of the century changed over time; from the 1st century BC through most of the imperial era it was reduced to 80 men." So if a century can have just 80 men, surely it can have just 99 years too! Gawaon (talk) 15:06, 4 January 2025 (UTC)

I agree the etymology argument is weak, but a century has 100 years, regardless of etymology. That's what we were all taught at school and that's what all credible sources say. Wikipedia should not take it upon itself to make up an exception. Dondervogel 2 (talk) 19:11, 4 January 2025 (UTC)

@Chessrat:

1) I actually don’t hate the idea of doing it your way, I just don’t see the need or the community interest. As you point out, socially and culturally we do treat it this way; we did have a special party on 31 Dec 1999, and not so much 31 Dec 2000. But the effort to shuffle it all around still comes with the need for a footnote explainer for our choice of convention and that now the 1st century is just the “first century” in name, and covers only 99 years. Honestly this is (imo) not a big deal, just not a hill I’d be looking to die on, and such a change will need a whole bunch of annoying cleanup. As everyone else has said, the old way has the seductive logic that 100=100. This area of Wikipedia especially was built early and therefore done so by those net-denizens more inclined towards “logic” than social convention.

2) As far as I know, articles on the subject of centuries are either covering the entire period broadly, or just giving a timeline of events that occurred in such years (or really, both). Presumably there’s not much worry whether we start with 1900 or 1901 when the topic is “world war, atomic energy, the end of empire, mass telecommunication and the beginnings of the internet” (etc). Alternatively, the specific events occurring on those crossover years is just arbitrarily dumped into whichever list-like article we like, and if it has carry-over effects on future events, that should get a mention either way. I guess this point (2) actually cuts both ways though, in the sense of “both work fine”. — HTGS (talk) 06:50, 3 January 2025 (UTC)

I assume by "we" you mean you personally. I also had a 31 Dec 1999 "2000" party, but my big millennium party for the century change came on Dec 31 2000. And my tickets to the event are on that date. Fyunck(click) (talk) 09:49, 3 January 2025 (UTC)

That’s honestly surprising to me. Whereabouts were you? I was in New Zealand, but my impression was that the big deal end-of-millenium in “Western” (global “North”? Anglosphere?) popular culture was 1999 to 2000. — HTGS (talk) 08:23, 4 January 2025 (UTC)

Yes, it would be a significant amount of work, but retaining an incorrect status quo is not desirable. If Wikipedia lasts to reach 2100, there would be the ludicrous scenario where it's impossible to cite the large number of sources stating the arrival of the 22nd century because Wikipedia policy defines the word "century" differently to the rest of the world.

You're probably right that regardless, a hatnote/explanatory note of some nature is needed. For instance, a lot of sources such as Reuters, The Telegraph, The Atlantic, The Guardian France 24, Times of Israel report that Emma Morano (1899–2017) was the last surviving person born in the 19th century. However, there are also a few sources such as Slate, the Washington Post, and Sky News which report that Nabi Tajima (1900–2018) was the last surviving person born in the 19th century, using the ending-in-1 definition.

At the moment, the implication of Wikipedia policy is that Tajima is described as having been the last person born in the 19th century on her article section, but Morano is not described as having been the last person born in the 19th century despite the numerous reliable sources stating that she was. The current policy effectively overrides any amount of sourcing of facts like that- every article treats the uncommon ending-in-1 definition as not only being a common definition but as the only definition. I don't see how a policy which arbitrarily overrides established facts and sources like that can possibly be justifiable. Chessrat ^{(talk, contributions)} 09:03, 3 January 2025 (UTC)

So your suggested change would also affect many other articles such as our own sourced 19th century article. Fyunck(click) (talk) 10:08, 3 January 2025 (UTC)

"but Morano is not described as having been the last person born in the 19th century despite the numerous reliable sources stating that she was." I question the reliability of a source that reveals such a failure at basic counting. --User:Khajidha (talk) (contributions) 16:15, 22 January 2025 (UTC)

Usage such as 20th century for 1900 - 1999 simply reveals the source as being unable to perform basic counting. Any such source is immediately rendered unreliable. --User:Khajidha (talk) (contributions) 13:06, 8 January 2025 (UTC)

I'm usually one to say that we should accept that language changes and that we in the language police should go along with it, but in this case, many, especially the mainstream press, looking for headlines, are wrong. Saying the first century has 99 years, is like saying 99 cents is sometimes a dollar. Sometimes a misused word becomes acceptable, but not in this case. SchreiberBike | ⌨ 14:42, 8 January 2025 (UTC)

As per WP:RS (with the emphasis on reliable), I asked Mr Google when does the new century start, then looked at any hit that seemed reliable (typically government or scientific time orientated organisations) and ignored anything like quora, mass media (I gave Scientific American a pass as they are scientific) and forums. The first 3 pages gave me the following list, plus I added the Greenwich observatory. Note, I choose them based on the sources before looking at what they said.

Organisation	URL	00 or 01
Hong Kong Observatory	https://www.hko.gov.hk/en/gts/time/centy-21-e.htm#:~:text=The%20second%20century%20started%20with,continue%20through%2031%20December%202100.	01
timeanddate.com	https://www.timeanddate.com/counters/mil2000.html	01
Scientific American	https://www.scientificamerican.com/article/when-is-the-beginning-of/	01
US Navy Astronomical Applications Department	https://aa.usno.navy.mil/faq/millennium	01
US Library of Congress	https://ask.loc.gov/science/faq/399936 https://www.loc.gov/rr//scitech/battle.html (Battle of the Centuries)	01
Merriam Webster	https://www.merriam-webster.com/grammar/centuries-and-how-to-refer-to-them	says it used to be 01 but that public opinion is swinging
Greenwich Observatory	http://www.thegreenwichmeridian.org/tgm/articles.php?article=12	01

Seems like the scientific community has a solid consensus on new centuries starting in the year xx01. The "Battle of the Centuries" is a good read. To be fair, does anybody have any authoritative sources backing the xx00 change date?

This is, of course, counter-intuitive to the layman who just sees 1999 tick over to 2000 and therefore assumes that change in the 3rd digit means a new century. But as we all know, intuition and truth do not always agree.

So why did the world celebrate the new century on 1 Jan 2000 ? I'm going to digress into armchair philosophising but bear with me. Image that you are a major newspaper, news channel, magazine, etc and you want readers to buy/subscribe. You can research it, find out that 1 Jan 2001 is the correct date and make a big thing on that date. But your competitors celebrated way back on 1 Jan 2000 and the public goes "meh, we did all that last year - get with the times you out of date moron!" The big news companies know this, so they all go with the earlier date to avoid their competitors getting the jump on them. Never let the truth get in the way of profit! Joe public naturally follows the mass media and ignores the nerds saying "2001" - why listen to boring nerds when you can party now! Party, party, party!

So, here we are, arguing whether to follow the truth or to follow Joe Public with both of his brain cells following news companies who are chasing the almighty dollar. Stepho talk 11:44, 3 January 2025 (UTC)

There are some known inconsistencies/anomalies in our treatment of centuries, including categories or articles covering decades. For example, Category:1900s in biology is a subcategory of Category:20th century in biology, but includes 1900 which the MOS puts in the 19th century. If we were starting again, I think it would have been better to avoid using century in categories or articles, e.g. use "1900–1999" instead of "20th century", but we are where we are. Peter coxhead (talk) 12:36, 3 January 2025 (UTC)

I'm not sure why you're focusing only on the specific niche of science-related sources? If the scientific community chooses to adopt an unorthodox definition of the duration of the centuries, but most other sources follow the common definition, obviously the latter is more accurate. Chessrat ^{(talk, contributions)} 13:45, 3 January 2025 (UTC)

@Chessrat: the century beginning in XX01 is not unorthodox, quite the reverse. As people above have said, it's the definition that has been taught for years, but one that I agree is increasingly being replaced by the century beginning in XX00 definition. Obviously the latter is more accurate, well, no – as pointed out above, this definition leads to the first century having only 99 years, so can hardly be called more accurate. Orthodoxy and accuracy are not the important issues in my view; the most important issue is what most readers now think 'century' means, which does appear to be the XX00–XX99 definition. Peter coxhead (talk) 14:21, 3 January 2025 (UTC)

Back in 2000 it was suggested that a year zero be created with (since years have variable numbers of days anyway) zero days. That way the first century would have 100 years in it. Hawkeye7 (discuss) 22:06, 3 January 2025 (UTC)

At least we can all agree that that would be the ugliest possible solution. — HTGS (talk) 08:26, 4 January 2025 (UTC)

I am a little confused, as it is the first year after 0. It's not the same as 0.1 in numbers. A child's first year is everything from being born until they have their first birthday, which marks the end of their first year.

This also fits with the 20th century being the years containing all the 19XXs (including 1900) and the first century being all the ones with 00XX or just X, XX and XXX !!

That means that the years 01-01-00 to 31-12-99 = 100 years. So let's just agree tha the first century har 99 years instead of 100. Simples.

Is this purely a case of missing "(not inclusive)"? 1900-2000 to me, means that when the number 2000 first appears on the timepiece, that is the end of the 20th century, and the start of the 21st - so midnight on the cusp of 31-12-1999 and 01-01-2000 would be the end of the 20th century.

All the months have a fixed number of days, except one every four years ... I'm really happy just considering that the 1st century only had 99 years. It's so long ago, and doesn't really matter as long as we all do the same thing. Lets just say that 1 BC is 0AD and 0BC is 1 AD. Chaosdruid (talk) 14:27, 19 January 2025 (UTC)

I cannot agree tha the first century har 99 years instead of 100. That defies logic. Instead, I shall propose this: can we agree that 1 BC was followed directly by 1 AD, and that there was no year zero? --Redrose64 🌹 (talk) 21:18, 19 January 2025 (UTC)

@Chaosdruid: A century has 100 years. Why is that so hard to understand?
@Redrose64: Yes to both.

Dondervogel 2 (talk) 21:46, 19 January 2025 (UTC)

But it is logical to carry on a mistake from one century into every other one ad infinitum rather than just apply logic like we do to February? Chaosdruid (talk) 10:00, 20 January 2025 (UTC)

Seems more like the February situation is the illogical one. And there is no mistake in the first place. "First century AD" has the simple meaning of "the first one hundred years counted as part of the AD era". If you count off said 100 years, it is the years 1 AD to 100 AD (inclusive). No more, no less. --User:Khajidha (talk) (contributions) 16:11, 22 January 2025 (UTC)

You realize that you paraphrase Humpty Dumpty here? ("When I use a word, it means just what I choose it to mean — neither more nor less.") In actual life, though, meaning is established through common usage, not by fiat of any single person or institution. So, if generally reliable newspapers and others consider all centuries (except for the first one) to start with a year (x)x00, that means something, whether you like it or not. Gawaon (talk) 04:19, 23 January 2025 (UTC)

Where do you get off saying that? Every newspaper I looked at on 1 January 2001 said the new millennium was just starting. They probably said the same thing in January 2000 so what that tells us is they are not reliable with this info. Fyunck(click) (talk) 08:10, 23 January 2025 (UTC)

No, I am not making words mean what I want them to mean. I am using the meanings of the words as given in dictionaries. First = with nothing before it in the sequence, AD = the anno domini system of labeling years, century = 100 years. There is no way to juggle the meanings of those words to avoid the years 1-100 AD being the first century AD. It is basic counting. --User:Khajidha (talk) (contributions) 12:41, 23 January 2025 (UTC)

You realise that newspapers (generally reliable or not) have a vested interested in reporting things first (see my explanation of this both above and below this reply). Which means that these otherwise generally reliable newspapers will agree with whichever year comes first. Repeating, they have a vested financial interested in pandering to centuries starting with 00.

Beware of mob rule. Many people confuse they're vs there vs their. Many people confuse 12:01 near lunchtime as am or pm. Many people confuse car brakes vs car breaks. Wrong doesn't always become right just by sheer numbers.

As opposed to practically 'every' scientific institute which follows 'truth' - complete with explanations when it is counter-intuitive (see my list of references above). This is not a fiat (ie, it is not an arbitrary choice) but a direct consequence of primary school maths. 07:52, 23 January 2025 (UTC) — Preceding unsigned comment added by Stepho-wrs (talk • contribs) 07:52, 23 January 2025 (UTC)

@Chessrat: Scientists put much thought into the matters that they comment upon, it's a poor scientist who states something as fact when they have no demonstrable evidence. So I would take a scientist's view over a newspaper's view any day. --Redrose64 🦌 (talk) 22:52, 3 January 2025 (UTC)

I just had another thought on the “why did the media prefer 2000?” question. At the time, there was a lot of concern over the Year 2000 problem, which had nothing to do with the official change to a new millennium. It would be easy to confuse the two, and the drama of the “Y2K bug” could easily have fed into hype about the new century/millennium.

Of course this could all be irrelevant if anyone has a couple of newspaper stories from 1899 talking the same story. — HTGS (talk) 20:14, 18 January 2025 (UTC)

The front page of the Daily Telegraph (a serious and respected global newspaper back then) from 1 January 1900, talking about the close of a century and the coming of a new one - largely in relation to Germany, it seems, with prescience given what was to come.[22] MapReader (talk) 07:57, 19 January 2025 (UTC)

I've already hypothesised on why the media preferred 2000 as the start of the new century but I will re-iterate. Assume you have smart employees that know 2001 is the real start and therefore your newspaper makes plans for a big celebration on 1 Jan 2001. Your competitors go with the 2000 date and the unwashed masses celebrate with them for many sales of their newspapers - yours gets mediocre sales because yours is boring. A year later you do celebrate but the unwashed masses say "we did that last year - loser!" Knowing that the unwashed masses will always go with the early date (no matter what the reason, any excuse for booze) and will ignore any repeat the next year (no matter what the reason), which is the better financial decision for the newspaper? Facts be damned, popular opinion makes money for newspapers! Stepho talk 09:37, 19 January 2025 (UTC)

Why would I care what idiots who can't count think?--User:Khajidha (talk) (contributions) 21:38, 19 January 2025 (UTC)

The analysis seems fairly straightforward to me:

It is pretty common for the inconsistent definition to be used, regardless of how respected its user is.
The inconsistency at the epoch generally goes unencountered, which means it is not a real problem. Nothing is meaningfully misunderstood by readers or writers most of the time.
Just because many don't run into the uncontroversial inconsistency, doesn't mean we are so lucky. We're enforcing style across the entire wiki, entailing thousands and millions of encounters with the epoch.
That means we each would like to understand what we're doing and why. Ergo, our choices tend to value logical consistency.
However, if we allow a convention, many editors will use it that do not fully understand it.
If we allow both the inconsistent and consistent definitions to be used, editors who see the former is valid usage in some locations will impose their preference elsewhere, leading to chaos and sorrow. This will occur regardless of whether the distinction is explained in the MOS itself.

Remsense ‥ 论 09:58, 19 January 2025 (UTC)

mdy on pages that have nothing to do with america

ive been seeing lots of mdy on pages that have nothing to do with the usa, like on media that was only released in japan, like the fds and lots of japanese exclusive video games

i just want the mdy stuff to be ONLY on usa related pages...

idk why we have to use multiple date formats here anyway... its just stupid

why cant we use just one... dmy for long form and iso 8601 for short form

japanese date format looks similar to iso 8601 if youve seen it ZacharyFDS (talk) 08:13, 14 January 2025 (UTC)

i did change a couple, like on the pcfx and .lb pages but im backing out of others because i dont want to be involved in edit wars or be accused of vandalism ZacharyFDS (talk) 08:15, 14 January 2025 (UTC)

The relevant guideline has a shortcut, MOS:DATEVAR. People who's main editing activity was to go around imposing their favorite date format have been indefinitely blocked. Jc3s5h (talk) 15:46, 14 January 2025 (UTC)

thats just stupid

idk about you but there should be an option for unifed date formats you can toggle in settings so users can use their perferred date formats without fighting over it. is it possible to yknow code something like this? ZacharyFDS (talk) 05:29, 17 January 2025 (UTC)

Unfortunately this is wishful thinking. We've looked into it many, many, many times before and it's just not doable with Wikipedia's current technology. One problem is that there are certain usages of comma with the mdy format that are really had to deal with when embedded in some sentences that use commas in certain ways - the computer just isn't smart enough to deal with it. The other is that we also have to handle users not logged in or without accounts - there is no preference to apply and it brings us back to which is the default and all the arguing that goes with that. Stepho talk 06:03, 17 January 2025 (UTC)

“the computer just isn't smart enough to deal with it” This actually surprises me. I wonder that a browser plugin or extension couldn’t solve this problem nicely without us on the Wikipedia side ever having to think about it again. I’ve had similar thoughts when someone inevitably comes along complaining that we don’t use British or American spelling (but mostly British), although that seems a fair bit harder. — HTGS (talk) 23:10, 23 January 2025 (UTC)

@ZacharyFDS: We did have such a feature, it was removed in 2008. I joined Wikipedia in May 2009, at a time when the clear-up was still going on. --Redrose64 🌹 (talk) 22:42, 17 January 2025 (UTC)

I want to emphasize that I supported removing that feature because it only worked if you were logged in to WP with an account AND had specified what format you preferred in your preferences. That meant that the vast majority of readers saw the default format. It required linking dates in a specific manner, which looked unusual and could be disrupted by editors who did not understand what the links were for. Donald Albury 01:57, 18 January 2025 (UTC)

I believe this is covered at WP:JDLI. Doremo (talk) 10:14, 14 January 2025 (UTC)
This issue is covered in the Manual of Style which stipulates what countries have which date styles. Here is what it says: Articles on topics with strong ties to a particular English-speaking country should generally use the more common date format for that country (month-first for the US, except in military usage; day-first for most others; articles related to Canada may use either consistently). Otherwise, do not change an article from one date format to the other without good reason. Because English is not a legal language in Japan, you might find the Japanese use American date formats when writing English. Look for an English language Japanese newspaper and see what they use. Avi8tor (talk) 12:46, 14 January 2025 (UTC)

It's because in English prose there are 2 dominant date formats: MDY used mostly by Americans and DMY used by most of the British Commonwealth. Both sides think that their version is the only correct and reasonable way and that anything else is stupid and wrong. So an article created by a Brit with DMY dates gets "corrected" by an American to MDY. And then "corrected" by an Australian to DMY. And then "corrected" by another American to DMY. And so on until all parties have a deeply embedded hatred for each other.

WP:DATERET was created so that once an article gets a format then it generally stays in that form and we avoid WP:EDITWARs (mostly - there are always die hard "do it my way" people out there).

We don't use Japanese YMD dates because no native English speaking country uses YMD in prose. Which is a shame because I love YMD after living in China. Stepho talk 12:56, 14 January 2025 (UTC)

Previous discussions on this talk page have made it clear that if a country isn't a predominantly English-speaking country, either MDY or DMY may be used. It just doesn't matter what the English-speaking minority within the country under discussion usually uses as their date format. Jc3s5h (talk) 15:50, 14 January 2025 (UTC)

all other countries use variants of dmy tho except for those east asian ones ZacharyFDS (talk) 05:34, 17 January 2025 (UTC)

No they don't. Many other countries use dmy. Some countries use entirely different calendars with different year numberings; for instance Iran still uses the Iranian calendars as its official calendar. Etc. Your assumption that "only that one country uses the other system and everyone else uses my system" is exactly the problem that WP:DATEVAR prevents. —David Eppstein (talk) 05:43, 17 January 2025 (UTC)

Pinging any Canadians: how annoyed does this discussion make you every time it happens? Remsense ‥ 论 20:16, 18 January 2025 (UTC)

oh yeah i forgot about iran (thats a variant of hijiri/islamic calendar)

im dumb can you forgive me ZacharyFDS (talk) 06:22, 18 January 2025 (UTC)

No worries - it looks real simple until you actually get into it. Stepho talk 08:54, 18 January 2025 (UTC)

Jc3s5h states the situation that has obtained back to the early days of en.WP. It keeps the peace: US editors can create articles that have little to do with any majority-Anglophone country, including the US, and expect that their initial choice will be retained. Same for vice versa. It's a reasonable policy and should be respected. My one issue is that if you try turning a US military article into dmy, sometimes you'll be shouted at. So I've learnt to leave the date formats in those articles as they are (even if they contain a mix of dmy and mdy). I wish they'd work out what they want. Tony (talk) 09:17, 18 January 2025 (UTC)

Yes we need clarity on US military. Giant Snowman 09:58, 18 January 2025 (UTC)

US astronomers (or at least the communications of the American Astronomical Society) also appear to use dmy. —David Eppstein (talk) 17:46, 18 January 2025 (UTC)

The astronomers themselves might, but their websites also might not; e.g. Palomar Observatory. --Redrose64 🌹 (talk) 18:43, 18 January 2025 (UTC)

Professional astronomers generally use yyyy/mm/dd. In fact they may even have been the originators of this format back in the days of George Airy at Greenwich.Skeptic2 (talk) 19:18, 18 January 2025 (UTC)

The US Army's Center of Military History Style Guide still mandates dmy, which is used internally, but mdy is acceptable in PR. As Tony says, we generally retain the existing format. Hawkeye7 (discuss) 19:14, 18 January 2025 (UTC)

RfC on the wording of MOS:CENTURY

Should MOS:CENTURY specify the start of a century or millennium as a year ending in 1 (e.g. the 20th century as 1901–2000), as a year ending in 0 (e.g. the 20th century as 1900–1999), or treat both as acceptable options with the use of hatnotes for clarity in the case of ambiguity in articles? See the discussion above. Chessrat ^{(talk, contributions)} 14:57, 3 January 2025 (UTC)

The year ending in zero, which is nowadays the most common understanding. Whether or not there was ever a year zero is irrelevant, given that AD year numbering wasn’t invented until the 500s and wasn’t widely used until the 800s. MapReader (talk) 21:21, 3 January 2025 (UTC)
As the 1st century is 1–100, the 20th century is 1901–2000, as its article says. Let us not turn this into another thing (like "billions") where English becomes inconsistent with other languages. —Kusma (talk) 22:22, 3 January 2025 (UTC)
Also, I do not understand what "hatnotes in case of ambiguity in articles" should mean: whenever any article uses the word "20th century", it should have a hatnote explaining whether it follows the centuries-old convention of numbering centuries or the "starts with 19 is 20th century" approximation? Perhaps it would be easier to outlaw the word "century". —Kusma (talk) 22:26, 3 January 2025 (UTC)

In short, oppose change. —Kusma (talk) 17:46, 4 January 2025 (UTC)
First year of a century ends in 01, last year of a century ends in 00. This has been extensively discussed above. --Redrose64 🦌 (talk) 22:52, 3 January 2025 (UTC)
The RfC does not make clear what specific change is being proposed to MOSNUM wording, and I fear will lead only to a continuation ad nauseum of the preceding discussion. For what it's worth, I oppose any change resulting in a century of 99 years. Dondervogel 2 (talk) 23:06, 3 January 2025 (UTC)
Oppose change Century and Millennia begin in 01 and ends Dec 31, 00, like it always has and per the discussion above. Just because people make errors, like with Blue Moon, doesn't mean an encyclopedia has to. Why would we change from long-standing consensus? Fyunck(click) (talk) 09:28, 4 January 2025 (UTC)
Treat both as acceptable options. Century already explains both viewpoints, without describing one of them as "correct". Generally our business it not to arbiter truth (which in this case doesn't exist anyway, as either viewpoint is just a convention), but to describe common understandings of the world, including disputes and disagreements where they exist. Century doesn't privilege a particular POV here, and neither should MOS:CENTURY. Gawaon (talk) 16:31, 4 January 2025 (UTC)
All of our articles on individual centuries mention only the traditional point of view where the first century starts in year 1 and each century has 100 years. There is no need for MOS:CENTURY to do anything else. —Kusma (talk) 17:46, 4 January 2025 (UTC)
Oppose. If this matters to you, convince the academic sources to adopt the change, then Wikipedia can follow. Jc3s5h (talk) 18:14, 4 January 2025 (UTC)
Oppose change I prefer centuries to begin with --01 and end with --00. I'll not bother with any arguments, since I think this boils down to personal preference. I do oppose allowing both options, as that leads to confusion and edit wars. Donald Albury 18:20, 4 January 2025 (UTC)
Why is it personal preference to favour 1-100 AD over 1 BC-99 AD? The latter choice leads to the first century BC running from 101 to 2 BC. I find the asymmetry highly unorthodox (and hence hard to justify). Dondervogel 2 (talk) 12:37, 6 January 2025 (UTC)
You wouldn’t start at 1BC for the first century AD in either case though. You would just treat “century” as the name for the period, and ignore that it only has 99 years. — HTGS (talk) 19:22, 6 January 2025 (UTC)
You seem to be saying the choice between a century (the first, whether AD or BC) of 99 or 100 years amounts to personal preference. Do you have credible sources showing they are equally valid? Dondervogel 2 (talk) 19:23, 7 January 2025 (UTC)
Oppose treating both as acceptable This would lead to endless confusion. Peter coxhead (talk) 22:02, 5 January 2025 (UTC)
Oppose change; century starts at ###1 and ends ###0 — Preceding unsigned comment added by Mr Serjeant Buzfuz (talk • contribs) 23:18, 5 January 2025 (UTC)
Strongly oppose any change resulting in more than one definition of a century. The reasons seem self-evident, and others have spelt them out above. In a nutshell, such a change would be a retrograde step, against the spirit of the MOS. Dondervogel 2 (talk) 23:21, 5 January 2025 (UTC)
Just use '00s. Why on Earth should MoS ever encourage using wording that will be misunderstood by many or most people? To most people, "20th century" means 1900-1999. To pedants of history, it means 1901-2000. Cool. We should try to not confuse either of those groups. If I had to pick one, I'd say confuse the pedants, but fortunately we don't have to pick, because a third option exists: "1900s" (etc.). That's the phrasing I've always used on Wikipedia, for this exact reason. It's consistent with how we refer to decades (see [23] vs. [24]). It's universally understood. It avoids silly arguments like this one. Let's just do that. -- Tamzin^{[cetacean needed]} (they|xe|🤷) 23:36, 5 January 2025 (UTC)
And to put this in terms of what the wording should be, I would suggest something like
Because phrases like the 18th century are ambiguous (sometimes used to mean 1700–1799, sometimes 1701–1800), phrases like the 1700s are preferable. If the former is be used—for instance, when quoting a source—an explanatory note should be included if the two definitions of nth century would lead to different meanings.
-- Tamzin^{[cetacean needed]} (they|xe|🤷) 23:52, 5 January 2025 (UTC)
Is this a joke? Sorry if I ruined it by asking. — HTGS (talk) 23:56, 5 January 2025 (UTC)
No? From any descriptive point of view, there is no widely-accepted definition of "nth century". Some Wikipedians thinking there should be a widely-accepted definition doesn't make it so. And MoS should not be in the business of encouraging ambiguous wording. Instead we should encourage solutions that avoid ambiguity, much as we do with ENGVAR. -- Tamzin^{[cetacean needed]} (they|xe|🤷) 00:05, 6 January 2025 (UTC)
Ah, sorry. This is all just not the question at hand though, and it directly contradicts current (well-positioned) guidance.

In any case, I’m sure we’re better off with the ambiguity between 1900–1999 and 1901–2000, which, in most cases, is not really a problem. Your idea introduces an ambiguity between 1900–1910 and 1900–[1999/2000]. This is explicitly called out by MOS:CENTURY, of course. And does “1700s” even solve the issue of which year to start or end with? It implies that the century starts with 1700, but not explicitly. — HTGS (talk) 03:05, 6 January 2025 (UTC)

We should avoid use of "1900s" to mean anything other than 1900-1909. Dondervogel 2 (talk) 12:29, 6 January 2025 (UTC)
What's funny is I have never heard people talk about the 1500s, 1600s, 1700s, 1800s or 1900s, as anything except Jan 1 00 to Dec 31 99. Always 100 years. I checked and I'm shocked our wikipedia article only covers 1900-1910. The only time it gets used as a decade is when the parameters are specifically talking about the 1930s, 1920s, 1910s, and 1900s. Without that fine tuning it's always 100 year period. It would be used like the Library of Congress does, or US history lesson plans. Usually I would say the "first decade of the 1900s" with no other context. I would amend your comment to say we should never leave 1900s dangling without context. And that's only for 1900s, not anything else.Fyunck(click) (talk) 19:36, 6 January 2025 (UTC)
Oppose treating both as acceptable; otherwise indifferent to 31 Dec 1999 vs 31 Dec 2000. This is a style decision, but one that affects a lot of content. To use both would be a terrible solution. — HTGS (talk) 23:52, 5 January 2025 (UTC)
Oppose change; continue using "20th century" for 1901–2000 and "1900s" for 1900–1999. Doremo (talk) 03:48, 6 January 2025 (UTC)
Bad solution. How will readers know which system we are using when we say 1900s? Will they presume that the period ends with 1999 or 2000, or even 1909? — HTGS (talk) 23:16, 13 January 2025 (UTC)
Oppose change - The n^th century is 01-00, you can feel free to use "the xx00s" for 00-99. Neither is prefered to the other, but the meaning is determined by which you use. Fieari (talk) 04:53, 6 January 2025 (UTC)
Per the MOS, and as Dondervogel 2 most succinctly puts it above: We should avoid use of "1900s" to mean anything other than 1900-1909. — HTGS (talk) 19:25, 6 January 2025 (UTC)
I somewhat disagree. It is a very ambiguous term so we should avoid use of 1900s at all without context, because obviously readers will be confused. I sure would since I would immediately think a 100 year period just like 1800s , 1700s, and 2000s (25+ years thus far). Fyunck(click) (talk) 07:16, 7 January 2025 (UTC)
You mean 24 years so far, right?

And yes, “avoiding 1900s at all” also jives with what I said. — HTGS (talk) 23:14, 13 January 2025 (UTC)
Oppose treating them both as acceptable. I imagine this could lead to headaches concerning inclusion in categories, list articles, timelines, templates, etc. Photos of Japan (talk) 01:23, 8 January 2025 (UTC)
Oppose change People have been getting it wrong for centuries (pun not intended) and will probably continue doing so for centuries. Intuition says that the year 2000 was the start of the new century but intuition is wrong. Just like people believing that light-years and parsecs are a measure of time (doing the Kessel run or otherwise) or trying to learn relativity, intuition is simply wrong. All authoritative sources for measuring time say that the new century starts in the year xx01. WP is only suppose to report on this. If we try to say that the year 2000 is the first year of the new century then we are actively entering the battle and are try to WP:RIGHTGREATWRONGS. Stepho talk 04:12, 10 January 2025 (UTC)
Keep XX1 as the start of a decade, century, or any other unit of year. It sounds ridiculous to have only the first CE century be 99 years long while everything before and after it remains at 100. —Tenryuu 🐲 ( 💬 • 📝 ) 18:34, 10 January 2025 (UTC)
I think they consider the 1st century BC to also have 99 years. Dondervogel 2 (talk) 19:15, 10 January 2025 (UTC)

It is high time to end this "minor imbecility":

When the encyclopedia of human folly comes to be written, a page must be reserved for the minor imbecility of the battle of the centuries--the clamorous dispute as to when a century ends. The present bibliography documents the controversy as it has arisen at the end of the 17th, 18th, and 19th centuries, as well as a few skirmishes in the quarrel that has begun to develop with the approach of the third millennium.

The source of the confusion is easy to discern; ever since learning how to write, we have dated our documents with year designations beginning with the digits 19. Obviously, when we must begin to date them starting with 20, we have embarked on a new century! Haven't we? The answer is no, we have not; we have merely arrived at the last year of the 20th century. As historians and others involved in measuring time continue to remind us, there was no year 0. In fact, there has never been a system of recording reigns, dynasties, or eras that did not designate its first year as the year 1. To complete a century, one must complete 100 years; the first century of our era ran from the beginning of A.D. 1 to the end of A.D. 100; the second century began with the year A.D. 101.

While the period 1900-1999 is of course a century, as is any period of 100 years, it is incorrect to label it the 20th century, which began January 1, 1901, and will end on December 31, 2000. Only then will the third millennium of our era begin.

Those who are unwilling to accept the clarity of simple arithmetic in this matter and who feel strongly that there is something amiss with the result have developed some impressively convoluted arguments to promote their point of view. Baron Hobhouse, studying some of these arguments as set forth in letters published in the Times of London during the first few days of January 1900, found "that many of the reasons assigned are irrelevant, many are destructive of the conclusion in support of which they are advanced, and that such as would be relevant and logical have no basis whatever to maintain them in point of fact." He was one of several observers of the fray at the end of the 19th century who predicted that the foolishness would recur with the advent of the year 2000, as people began to look for ways of demonstrating "that 1999 years make up 20 centuries."

As a writer stated in the January 13, 1900, Scientific American, "It is a venerable error, long-lived and perhaps immortal." The shortness of human life is also a factor; as a century approaches its end, hardly anyone who experienced the previous conflict is still living, so we are doomed to undergo another round.

Astronomers have been blamed for some of the confusion by their adoption of a chronology that designates the year 1 B.C. as 0 and gives the preceding years negative numbers, e.g., 2 B.C. becomes -1, 3 B.C. becomes -2, etc. This system permits them to simplify calculations of recurring astronomical events that cross the starting point of our era, such as series of solar eclipses and the apparitions of periodic comets. However, this scheme affects only the years preceding A.D. 1 and cannot be used as a justification for ending subsequent centuries with the 99th year.

Some argue that Dionysius Exiguus made a mistake in his determination of the year of Christ's birth when he devised our present chronology in the sixth century, and that the discrepancy allows us to celebrate the end of a century a year early. However, even though the starting point of our era may not correspond to the chronologist's intention, it is still the point from which we count our centuries--each of which still requires 100 years for completion.

Nevertheless, as many of the entries in this list (from p. 45 on) will indicate, plans to celebrate the opening of the 21st century and the third millennium at midnight on December 31, 1999, have become so widespread that anyone who tries to call attention to the error is disparaged as a pedant and ignored. Perhaps the only consolation for those intending to observe the correct date is that hotels, cruise ships, supersonic aircraft, and other facilities may be less crowded at the end of the year 2000.

Dondervogel 2 (talk) 18:04, 10 January 2025 (UTC)

Oppose change. Tony (talk) 11:46, 11 January 2025 (UTC)
Don't break the calendar for exactly zero benefit – There's no need to stage a revolt against the counting numbers and anyone who wants to extend discussions back to the epoch or beyond. There is one system that is consistent, and it is the one we use and should continue using. There's not even a problem that needs to be addressed. Aren't we on Wikipedia? This is the place where many often learn that a thing is a certain way and why, and I am not sure why that didn't happen here. Remsense ‥ 论 12:00, 11 January 2025 (UTC)
To get literal, the current calendar under discussion pertains to the life of Jesus. Ideally it starts when Jesus was born, 00:00, and he turned one-year-old on January 1, 1. Now, say he lived a long life and made it to 100. He would have been 100 on January 1, 100. At that point, the second his clock turned over on January 1, 100, his new century would begin. The first century was literally over on January 1, 100, and a new one started immediately and ran from 100-200. etc. Saying the first century was 99 years is incorrect, it was 100, but then the second century started immediately. I'd have to go with a split-second past midnight on January 1, 2000, as the start of the 21st century, per logic and common sense. Randy Kryn (talk) 13:30, 11 January 2025 (UTC)
Nice theory, except for the minor detail that there was no year zero, meaning that on 1 January 1, your hypothetical Jesus would have been 1 day (not 1 year) old. Dondervogel 2 (talk) 13:42, 11 January 2025 (UTC)
That's one way of looking at it, and the other is that Jesus's birth started the clock rolling towards his turning 1-year-old on 1-1-1. Randy Kryn (talk) 14:42, 11 January 2025 (UTC)
So by your "other way" he was 1 year old throughout 1 CE. So in what year was he six months old? It would have to be 0 CE, but there isn't one. It simply doesn't work. Peter coxhead (talk) 16:38, 11 January 2025 (UTC)
Unless our baby Jesus was born on 1 Jan of 1 BC (we have invented a fictitious baby so we can assign him any date of birth we want). Then we have a first century running from 1 BC to 99 AD. While highly unconventional, it could be entertained until you realise the 1st century BC would have to run from 101 BC to 2 BC. It works but it's silly, and (more to the point) lacks RS to support it. Dondervogel 2 (talk) 17:23, 11 January 2025 (UTC)
Insofar a he is likely to have existed, anyway, he was most probably born in 4 BC, since the calculations used five hundred years later to fix the BC/AD break point contained an error. So this is all nonsense, anyway; the first century was itself centuries in the past - probably eight or nine - before people started calling it that. And most people will continue to see 1900 as the start of the 20th C and 2000 as the start of the current one, whatever. MapReader (talk) 18:29, 11 January 2025 (UTC)
The bible is very clear on this point: he was born after the Roman census in 6 AD (Luke 2:1-4) and before the death of King Herod in 6 BC (Matthew 2) Hawkeye7 (discuss) 06:06, 12 January 2025 (UTC)
I think you mean the Census of Quirinius in 6 BC, while Herod the Great gives Herod's death as c. 4 BC. Donald Albury 14:56, 12 January 2025 (UTC)
That would make for a more consistent timeline. Forgetting our fictional baby, are you saying the Real McCoy was born between 6 and 4 BC? Dondervogel 2 (talk) 15:21, 12 January 2025 (UTC)
That's what many sources I've seen say. See Date of the birth of Jesus. Donald Albury 15:50, 12 January 2025 (UTC)

That make a lot more sense than being born before –6 and after +6. Although, if anyone could, surely it’s the son of God. — HTGS (talk) 23:39, 12 January 2025 (UTC)

Why would Jesus be one year old throughout 1 AD? The year 1 means Jesus was 1-year-old, Happy Birthday on 1-1-1, one candle on the cake. When Jesus was six months old he was 1/2 AD. The point of using BC and AD, before Christ and Anno Domini, logically informs that the time before Jesus's birth, counting backwards, was "before Christ" (six months before his birth was 1/2 BC, etc.) The birth starts the count on both BC and AD. The "year" he was born would not matter, only the counting forwards and backwards. 1/2 AD when he was six months old, 3/4 AD at nine months old, etc., until reaching 1 AD and then beyond. Another point, since the 21st century was celebrated by the entire population of the Earth on January 1, 2000 - even most of the 2001 holdouts, never ones to pass up a good party, still celebrated on 1-1-2000 - that date is the "common name" for the start of the century and, per many of the reputable sources mentioned in the discussion preceding this RfC, and in all the reputable sources that recognized the date that the human race partied, Wikipedia probably should as well. But, then again, and Oppose, the scientific community differs and happily celebrated on January 1, 2001, ordaining that Wikipedia should keep the academic calendar as well and forego the obvious. Randy Kryn (talk) 02:47, 12 January 2025 (UTC)
You can keep discussing this forever. Come 2100, when almost all of us will no longer be editing on here, the large majority of people will be marking the turn of the century. MapReader (talk) 15:09, 12 January 2025 (UTC)
Nice crystal ball you have there. Donald Albury 15:52, 12 January 2025 (UTC)

@Randy Kryn: For the sake of argument, if Jesus was born on 25 December 1 BC, he would have been six days old on 1 January AD 1, and one year old on 25 December AD 1. That would place the 100th anniversary of his birth on 25 December AD 100. Donald Albury 15:15, 12 January 2025 (UTC)
But 25 December is irrelevant, and is hence ignored by those faiths, such as Islam, that recognise Jesus as an earlier prophet. December 25 is an entirely fabricated date, chosen to override the pre-existing pagan midwinter festivals widely observed in Europe during the early Christian era. If early historians were four to six years out on the year Jesus was purportedly born, they are hardly likely to have any information whatsoever as to the date. MapReader (talk) 15:21, 12 January 2025 (UTC)

December 25 has nothing to do with this. The people who created this BC-AD concept were going by the moment that Jesus was born (or conceived, whatever they decided was the starting point), never mind the "correct date", in essence calling that Day One. Then, 365 days later, year 1 ended and year 2 immediately began. The same with BC, from the moment of Jesus' birth to everything that came before was BC, and one year previously was automatically 1 BC, ten years was 10 BC, etc. By calculating that the day of Jesus' birth was the start of the calendar, logic dictates that the first year ended on his first birthday. 1 A.D. Nothing is broken here, except that they made a guess at Jesus's birthday when they made the calendar. The first century of 100 years ends on the 100th anniversary of Jesus' birth, 1-1-100, and the second century began immediately. There is no "year 0", a year 0 isn't needed, when Jesus was six months old it was 1/2 A.D. The absence of a year 0 is incorrect, the creator of the calendar took it as a moment in time (a birth, then start the clock). Randy Kryn (talk) 10:28, 13 January 2025 (UTC)

"he turned one-year-old on January 1, 1".. No, that's not how that works. The year 1 AD is the equivalent of the first year of his life. He would not be 1 year old until it ended. User:Khajidha (talk) (contributions) 14:17, 14 January 2025 (UTC)
Oppose. Only ignorant people think the century begins with the 0 year. Is it that difficult to appreciate that there was no year 0! -- Necrothesp (talk) 11:44, 13 January 2025 (UTC)
However, few people will doubt that there was a year 2000. So the question of when the 21st century began it still unresolved. Gawaon (talk) 04:25, 14 January 2025 (UTC)
If the 1st century began in AD 1, then the 2nd century began in AD 101, the 3rd century in AD 201, etc, etc, the 20th century in 1901 and the 21st century in 2001! People a century ago were fully aware that the 20th century began in 1901. It's only in recent years that people have seemingly become unable to grasp the system. I should also point out that we naturally count in multiples of 10: 1 to 10, 11 to 20 and 21 to 30, not 10 to 19 and 20 to 29. -- Necrothesp (talk) 11:16, 14 January 2025 (UTC)

Looks resolved by consensus to me. Fyunck(click) (talk) 06:59, 14 January 2025 (UTC)
Yes, this has consensus, but nobody has actually refuted my discussion points above. There is no need for a year 0, the "point of zero" was when Jesus was born (which started the clock). He was 1 year old on 1-1-1. And so on. Necrothesp calls me ignorant, so I'd like them to comment if they would on the analysis of why year 1 started exactly a year after the birth of Jesus. Thanks. Randy Kryn (talk) 11:08, 14 January 2025 (UTC)
You presumably do know that the year before AD 1 was 1 BC? We're talking history here, not religion. Basing the calendar on the supposed year of Jesus's birth is pure convention. But the facts are that in the modern dating system 1 BC was followed by AD 1 with no weird gap. Therefore, the 1st century AD began on 1 January AD 1, and the new century has begun on 1 January AD X(X)01 ever since. -- Necrothesp (talk) 11:16, 14 January 2025 (UTC)
BC literally means "before Christ". Year 1 B.C. would be a year before Christ. Year 1 AD would fall on his first birthday. There is no weird gap. BC was created without regard to previous calendars, it just shifted all of the years before Jesus' birth and after Jesus' birth to a new counting system. This has nothing to do with religion or the exact year or date that is now believed to be Jesus's true birthday, it was just how the people who created this system decided to place their 0: the moment Jesus was born. As I say above, I agree with the consensus here, mainly because science has, for some reason, gone along with 2001 etc. being the start of a new century. It wasn't, but that counting system has enough support to continue to represent this mistake in scientific and encyclopedic literature. Randy Kryn (talk) 11:36, 14 January 2025 (UTC)
There is I believe no year zero because the Roman's (whose numerals we used) had no concept of Zero, there was no zero year, it was 1 BC then 1 AD. Avi8tor (talk) 12:54, 14 January 2025 (UTC)
But whether or not there was a year zero is pretty much irrelevant, except to the pedants overrepresented amongst our editor base. People are quite happy that the ‘1930s’ refers to 1930-39 and the ‘1630s’ to 1630-39, yet if you follow that right back the first decade only had nine years. So what? Stuff that happened, or works that were produced, in 2000 are widely referred to - including in WP articles - as being of the 21st century, because that’s the way most people see it. MapReader (talk) 13:58, 14 January 2025 (UTC)
You are confusing 2 different systems. Decades are named cardinally, centuries are named ordinally. The 1930s refers to 1930-39 for the simple reason those are the only years of the format 193X. However, the "first decade" refers to the first ten years of the system. Thus it means the years 1-10, just as the first century means the years 1-100. Decades and centuries are handled differently and do not line up. The 1900s decade was the years 1900-1909, and included one year from the 19th century and 9 years from the 20th. The first decade of the 20th century was the years 1901-10. User:Khajidha (talk) (contributions) 14:22, 14 January 2025 (UTC)
Yet, back here in the real world, nobody cares, and everybody ignores stuff like that. MapReader (talk) 14:26, 14 January 2025 (UTC)
The "real world" in your view presumably refers to "what I say" rather than "what is correct"! In my real world, the 21st century began in 2001! That's not being pedantic; that's being correct. In this fabled "real world", most people seem to get their "facts" from some nobody on TikTok; that does not make them right. -- Necrothesp (talk) 15:44, 14 January 2025 (UTC)

In the real world people also talk about things happening on "Friday night" when they actually occur in the early hours of Saturday. The encyclopedia still goes with the facts, though. --User:Khajidha (talk) (contributions) 16:29, 14 January 2025 (UTC)
Technically the 20th century is 1901–2000, but if you mean a specific date range such that precision to within one year matters, you are better off explicitly writing the start and end year (and adding "inclusive" to be extra sure). — A. di M. 08:33, 21 January 2025 (UTC)

Collision between understandings of MOS:ERA : does the style or notation "first used in article" have absolute priority over all other considerations?

Crossfire1776 and I have an irreconcilable difference of interpretation of MOS:ERA. As I understand it, their view is that an article should use AD notation if that was the style first used, no matter how long ago and there is no need to consult before reinstating it. My reading is that long-established practice should not be changed without first securing consensus at the article talk page. We have discussed the issue at length at User talk:Crossfire1776#January 2025 but have reached deadlock. As the issue is a generic one, it has not been discussed at any single talk page but the edit summary on diffs like this one may be relevant.

We asked for a wp:Third opinion but the request was declined because there are more than two parties to the dispute. It doesn't make sense to refer to full Dispute Resolution as it is not really a content dispute, more a question of interpretation of the MOS. Is it an appropriate topic for this talk page instead? 𝕁𝕄𝔽 (talk) 14:03, 6 February 2025 (UTC)

Yes, I think this is a suitable place. And JMF I think comments about what religious views editors might have are irrelevant and inappropriate. Sweet6970 (talk) 14:30, 6 February 2025 (UTC)

Thank you and yes, I acknowledge that failed to WP:AGF in that case and, to minimise distraction, will go back and strike it. 𝕁𝕄𝔽 (talk) 14:43, 6 February 2025 (UTC)

Thank you. Sweet6970 (talk) 14:56, 6 February 2025 (UTC)

In my opinion, AD and CE are equally Christian systems given their choice of epoch, and there's no getting around that with a label swap. There's exactly one topic area where a substantive case can be made for switching between era systems, though I would still oppose it all else being equal: given that "Christ" refers very specifically to the completion of a core tenet within Judaism, I respect the argument that articles concerning Jewish topics would be better off not implicitly referencing a claim to that completion that Jews consider to be comprehensively false.

However, others have differing opinions based on e.g. what's used in sources, with which I strongly disagree. However, in my view the present verbiage essentially functions a release valve allowing for relatively harmless local consensus while preventing almost all potential arguments, keeping everyone as sane as possible. Remsense ‥ 论 14:54, 6 February 2025 (UTC)

Concerning the disagreement most relevant here, I think to get along you have to recognize that the point of the present verbiage is to avoid patterns of disruption by presenting a default no one can argue with. There are cases where adhering to the letter is in effect clearly generating that disruption instead of putting it to rest. I would like to imagine some deference would be paid to the major contributors who worked on getting an article to its present state. Remsense ‥ 论 14:56, 6 February 2025 (UTC)

@Remsense: You are now addressing the general question of AD v CE, whereas JMF has raised a specific, narrower question – whether the first usage in an article should be followed, or whether a usage can be validly established if it is unchallenged for some time. Let’s stick to the narrow question. Sweet6970 (talk) 15:02, 6 February 2025 (UTC)

That's my second comment. Remsense ‥ 论 15:03, 6 February 2025 (UTC)

No, they are not equally Christian. While the expansion of AD, Anno Domini, asserts allegiance to the central figure of Christianity, the expansion of CE, Common Era, merely asserts that the Gregorian Calendar is in widespread use.

That said, the issue of whether long time use establishes consensus for purposes of wiki policy may be above our pay grade. -- Shmuel (Seymour J.) Metz Username:Chatul (talk) 18:47, 6 February 2025 (UTC)

What's common about this era, exactly?

An illustrative exercise: if we adopted the epoch of the Islamic calendar, but decided to relabel the present era as "CE" instead of "AH", I don't think it would be controversial that the system remains an Islamic one: both AH and AD are equally arbitrary and equally viable for adapting to secular use, but it is not possible to avoid or make transparent what event each epoch was meant to correspond with. Remsense ‥ 论 19:26, 6 February 2025 (UTC)

It is the "common era" because it is used in international dealings by countries of all religious backgrounds. The Islamic calendar is (to my knowledge) only used in and between Islamic countries. If that were to change, and the AH era become the worldwide dominant form the way the AD era did, I would have no objection to using a term like "common era" to designate it. --User:Khajidha (talk) (contributions) 18:51, 7 February 2025 (UTC)

I don't think there is a clear answer, for style that is supposed to be retained, such as era, national variety of English, or date format, whether a long period of silent acceptance of a change to the original style establishes the new style.

In order to respect editor's time and effort, I think we should not allow silent changes, because it is too much effort for editors to slog through all the edits, half of which are vandalism, to figure out whether a new style has been established or not. It's hard enough to find the first usage. I think the rule should be first usage or a talk page discussion with a clearly relevant heading. If a discussion establishes CE as the style for an article but the heading is "Noxious edits by XYZZY7369245" it doesn't count. Jc3s5h (talk) 17:21, 6 February 2025 (UTC)

I think if an article is or has consistently been inconsistent, or has been subject to constant warring back and forth, an unannounced reversion to the initial era format is acceptable. If an article has, say, spent 12 of its 14-year existence as the other format, passed GAN in that time, or otherwise essentially assumed its present status using the "wrong" format, then that is clearly tantamount to local consensus and it would be best to ask or announce first. Remsense ‥ 论 17:25, 6 February 2025 (UTC)

Sounds sensible. But I don't like the idea that the existence, even for years in a longish article, of mixed styles should make a non-original style "established". Most people can't be bothered noticing, complaining or correcting "wrong" styles. The fact is, the vast majority of era changes are done in ignorance or defiance of the rules, and I give the first-used style a strong preference. Or there should be a discussion, which if properly adveertised trumps everything. From past experience, and most mysteriously, 𝕁𝕄𝔽 mostly sees illegal changes from BCE to BC, while I mostly see ones the other way, like this guy just now - all his edits are "Update BC to BCE" etc. Johnbod (talk) 18:54, 6 February 2025 (UTC)

I feel that way also. In short, if a major contributor is only used to one style and wants it switched back, that's a good enough substitute for me. Remsense ‥ 论 01:02, 7 February 2025 (UTC)

If I may return attention to my original question: MOS:ERA (like MOS:ENGVAR) was introduced to head off silly I LIKE IT/I DON'T LIKE IT edit wars, so let's not get sidetracked into the pros and cons of either system: Wikipedia documents what is, not what should be.
MOS:ERA currently states:

An article's established era style should not be changed without reasons specific to its content; seek consensus on the talk page first (applying Wikipedia:Manual of Style § Retaining existing styles) by opening a discussion under a heading using the word era, or another similarly expressive heading, and briefly stating why the style should be changed.

So why do we bother to make that statement, if there is a trump card (first use) that can always overturn it? What constitutes "established style"? (and where, btw, is the "first used" rule? "Everybody knows", but where is it? --𝕁𝕄𝔽 (talk) 20:18, 6 February 2025 (UTC)

Alas, putting it in MOS doesn't head of edit wars, because some editors don't consider themselves bound by MOS policies that they disagree with, e.g., use of present tense rather than past tense when describing things no longer in production. -- Shmuel (Seymour J.) Metz Username:Chatul (talk) 19:31, 7 February 2025 (UTC)

First use does not have absolute priority, it's just the last tie breaker. Consensus can override it. I looked through the history for the last 5 years and it was "B.C." for at least the last 5 years. Nobody challenged it for at least 5 years, so that's a defacto consensus. The only proper way to change it now is to raise it on the talk page and get a new consensus - although I see no valid reason why either system would better suit the article, so it would be a time waster. Stepho talk 00:47, 7 February 2025 (UTC)

I agree. Clearly an era style that has been used for years is the "established era style" and no editor should change it without seeking talk page consensus first. It's exactly such kind of unproductive editing that MOS:ERA is meant to prevent. Gawaon (talk) 03:35, 7 February 2025 (UTC)

No, this is what I don't like. 5 years is not long enough to make a style "established", especially if it was changed illegally. Many of our articles are now over 20 years old, & if such an article spent 15 years as style A, then was "illegally" changed to style B, and nobody complained for the subsequent 5 years, it should still be changed back. JMF, your first question is rather silly - as pointed out above first use is not a trump card, & a new consensus can always over-ride it. Surely you know this by now - you've been arguing about the issue for at least a decade? The 2nd question "What constitutes "established style"?" is indeed afaik not actually set out anywhere. I've seen short and long periods mentioned in discussions - I favour long ones, so 5 yrs may not be enough. The policy is rightly written to avoid legitimizing rule-breaking. Johnbod (talk) 06:09, 7 February 2025 (UTC)

@Johnbod: (and Jc3s5h), I believe I have been scrupulously neutral in reverting illegal changes, both ways, and that you have probably seen me do so. Yes, I prefer the secular or non-denominational notation but no, I do not try to WP:RGW by imposing it or indeed applying a notation at all, when no ambiguity arises. Nor do I go round on a hunting expedition, as Crossfire1776 has been doing, looking at every instance where AD/BC is used, to see if I can establish prior use of CE/BCE and enforce it without further ado. I would consider that to be unproductive editing. --𝕁𝕄𝔽 (talk) 11:31, 7 February 2025 (UTC)

If nobody complained about a change for at least 5 years then either nobody cared about the change or nobody cared about the article. In both cases it didn't cause an upset, so it has become the consensus. The time to complain about a change (assuming that the end result is still within MOS) is when it was made, not years after. Otherwise we need to look at every single edit done in the early years to see when BC was introduced (a tedious task) and also check any archives for discussions, plus any further edits after consensus (if any) to see if/when it was changed - all tedious for no real gain.

Pragmatically, it is far, far easier to consider any change that is unchallenged for a few months to be the new consensus - which also follows in the spirit of WP:BRD. Remember that the point is not to remove a change to an invalid format but to discourage edit wars over 2 valid formats. Arguing over a change from many years ago seems like a great way to start edit wars.

I also followed some more history of that article back to 2012. That's 12 years (at least) of the same format being unchallenged. Stepho talk 06:52, 7 February 2025 (UTC)

So am I correct to recognise the essence of the discussion above is that that the "first used" principle may be used to revert an illegal change, no matter how long ago it was made, and no discussion is required. However, editors of the page concerned may discuss (or have already discussed) which is the most appropriate notation to use and it is the consensus arising from that debate which becomes the "established style" for the article. Consequently, anyone who seeks to change the style (citing the first-used principle) must demonstrate that they have searched the talk page archives to verify that the topic was not previously discussed and agreed and can show that the change was indeed illegal. --𝕁𝕄𝔽 (talk) 11:31, 7 February 2025 (UTC)

No - of course not. Anyone can start a discussion for any reason, including (in fact much the most usual) their prejudice that one or the other style is "correct". The styles used in the past may well be raised in the discussion, as apart from prejudice there are actually rarely any substantive arguments for one over the other. Johnbod (talk) 16:28, 7 February 2025 (UTC)

So if I might clarify as a relative layman first use principle applies if the change was not discussed in the talk page e.g. if a person swapped the usage without asking people beforehand but if their was a discussion on the article and people agreed to change the dates then you need to reach consesus on the talks page first in order to change it.

That seems reasonable to me and I'm happy to accept those terms. Although I am unsure how to show you searched the talks page to see if it was ever discussed before as that is proving a negative and I don't see how you can link to a discussion that did not happen. Crossfire1776 (talk) 11:48, 7 February 2025 (UTC)

We WP:assume good faith. If you assert in your edit summary that you have checked the talk page history, then we will take your word for it. 𝕁𝕄𝔽 (talk) 11:58, 7 February 2025 (UTC)

This whole issue of "legality" is pointless and leads nowhere. Any change that persisted over months or years without being challenged passes WP:EDITCON and so could only be challenged if the resulting end state doesn't comply with the MOS (but both era styles do) or other rules of ours. Whether or not prior talk page consensus was sought is at that point entirely irrelevant – the consensus has been established post facto by the edit not being reverted within a reasonable timeframe. Gawaon (talk) 11:59, 7 February 2025 (UTC)

Fortunately this is not what policy says, nor is it what usually happens. Otherwise people with strong views would constantly be changing styles & hoping it sticks. There is quite a lot of that going on in fact, but I think mostly arising from ignorance of our policies, or that anyone could object. In fact the status quo is generally effective, and serious disputes not common. Very often disputes involve styles that have been mixed for a long time. Johnbod (talk) 16:28, 7 February 2025 (UTC)

Well, if the style in a page is mixed, then EDITCON has simply not yet emerged. Gawaon (talk) 17:03, 7 February 2025 (UTC)

It is something of a fantasy to think of a "consensus style" not having "emerged"! Huge numbers of articles have mixed styles in this as in as in US/Brit spelling, almost invariably because some very likely inexperienced editor has added something in the style that comes naturally to them, without giving any thought to consistency, wiki-policy etc. Johnbod (talk) 20:33, 7 February 2025 (UTC)

Yet the activity that gave rise to this question was an editor working methodically though the list of articles that link the the Common Era article, searching the history for evidence of prior use of AD. There is no reason why similarly motivated editors couldn't do the same to uses of metric, of US/UK spelling, 24 hour clock times, YMD/MDY/DMY dates etc etc. A bot could do it, just slowly enough not to be identified as such. I would like to be able to say that this is just a reductio ad absurdum for didactic purposes, but we have already reached the absurd. We need to be able to draw a line, such as Stepho-wrs has proposed. --𝕁𝕄𝔽 (talk) 20:25, 7 February 2025 (UTC)

and just in case I need to state the obvious, the analysis and conclusions in this case apply equally to the SI v USCU/Imperial measures and the ENGVAR issues too. At least. 𝕁𝕄𝔽 (talk) 13:41, 7 February 2025 (UTC)

And to date formats? If the implications are this far-reaching, should the discussion be promoted to MOS? Dondervogel 2 (talk) 13:57, 7 February 2025 (UTC)

I (vaguely) remember we had the same discussion regarding DATEVAR, with the same conclusion: Force-changing an established style (stable for years) is against the spirit (if maybe not the letter) of the rule, so EDITCON beats whatever people may read out of DATEVAR, and consulting an article's ancient history to challenge a well-established style is not welcome. Gawaon (talk) 14:29, 7 February 2025 (UTC)

Question about MOS:TIME

MOS:TIME encourages us to use 2:30{{nbsp}}p.m.. Would we also use {{nbsp}} for 2 p.m.? Whatever the answer, could it be added to MOS:TIME? Thanks! GoingBatty (talk) 23:08, 8 February 2025 (UTC)

It seems facially unacceptable for a passage to have "2" and "p.m." broken up across successive lines. Remsense ‥ 论 23:11, 8 February 2025 (UTC)

To me, 2 p.m. seems too informal for an encyclopedia. I would require 2:00 p.m. --User:Khajidha (talk) (contributions) 23:38, 8 February 2025 (UTC)

To me, that potentially implies precision when it's not required to do so. I think it's perfectly fine in some contexts to state round figures without an "estimated" or "approximately", but why exclude the less precise form as an option? I have no real sense why it would be "informal"—that would seem vaguely akin to copyeditors mechanistically replacing "called” with "referred to as" or "bigger" with "larger" as if simple expressions are inherently less formal. Remsense ‥ 论 23:46, 8 February 2025 (UTC)

And I definitely find "bigger" to be too informal for encyclopedic writing. --User:Khajidha (talk) (contributions) 00:08, 9 February 2025 (UTC)

I don't think there's any real lexical or usage evidence for that position, but I understand the impulse.

[Sidebar: I had assumed big was longstanding Germanic vocabulary, but apparently it's shifted from meaning 'powerful' more recently, and great is (of course) the Old English term that would generally be used with the sense of 'large'.] Remsense ‥ 论 00:09, 9 February 2025 (UTC)

MOS:TIME says that 12 hour times should have a non-breaking space before the am or pm. It doesn't give an hour-only example in that paragraph but neither does it qualify it in anyway - so non-breaking spaces should always be used (I'd be tempted to use {{nowrap|2 p.m.}}).

It does give an example of 11 a.m. - so that implicitly says that 2 p.m. is perfectly valid. Stepho talk 02:12, 9 February 2025 (UTC)

Unregistered units not allowed to edit articles?

Just wondering why standard units are not allowed to be added to articles by unregistered users? I added the predominant units used in the Anglosphere. On English language Wikipedia. As WP:UNITS indeed appears to allow. 142.120.196.175 (talk) 21:33, 12 February 2025 (UTC)

It has nothing to do with being unregistered. Your edits would have been reverted regardless. They added imperial units to non-US-related articles, which is not "the predominant units used in the Anglosphere" and not encouraged by MOS:UNITS. —David Eppstein (talk) 21:50, 12 February 2025 (UTC)

On the contrary. MOS:CONVERSIONS directs users to include conversions in brackets after the main unit on most articles, and that's what the IP was doing. The issue with the IP's edits were that the customary units were generally not properly formatted, and they would have been better off doing the job using {{convert}}. Kahastok talk 18:55, 13 February 2025 (UTC)

Some of them were ... strange (example). --Redrose64 🌹 (talk) 18:04, 14 February 2025 (UTC)

^ Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.

[NUBASE2020-1] Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.

[1]