# Wikipedia talk:Manual of Style (dates and numbers)/Archive 24

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This discussion about the units section continues from archive 23.

## Units section, continued

### Vote on revision to 'Units' section in Manual of style

The clear and present problem that has been identified recently in Wikipedia editing is that some editors want to remove or prohibit metric units and other editors want to see metric units. We need to answer the question: Does the Manual of Style permit removal of metric units? The Manual of Style response is currently inconsistent, ambiguous and subjective. For the last two weeks we have been discussing ways of resolving this problem. The proposal that has been under discussion is consistent, unambiguous and objective. Please vote between now and 31 July on whether you would like to replace the entire units section with:

Wikipedia articles are intended for people anywhere in the world. Try to make articles simple to read and translate.
• Metric units are permitted. This applies to all parts of all articles.
• Non-metric units are permitted. This applies to all parts of all articles.
• Try to get the best source value (e.g. from manufacturer's specifications). Write the source value first and then the converted value. Use digits and unit symbols for the converted value. For example, '100 millimetre (4 in) pipe for 10 miles (16 km)'. This means that the source values are 100 millimetres and 10 miles.
• Converted values should use a similar level of precision as the source value. For example, "the Moon is 400,000 km (250,000 miles) from Earth", not "(248,548.477 miles)".
• Use standard symbols when using symbols: metre is 'm', kilogram is 'kg', inch is 'in' (not " or ″), foot is 'ft' (not ' or ′)
• Do not append an s for plurals of unit abbreviations. Thus 'kg', 'in', 'yd', 'lb' not 'kgs', 'ins', 'yds', 'lbs'.
• Non-metric units often have more than one version. Be specific. Thus 'US gallon' or 'imperial gallon' rather than just 'gallon'. Similarly, 'nautical mile' or 'statute mile' rather than just 'mile' in aviation, space, sea and some other contexts.
• The reader should see a space between the value and the unit symbol, for example "25 kg" not "25kg".

#### Vote

For

1. Bobblewik 19:00, 23 July 2005 (UTC)

Against

#### Alternative proposals

1. Atleast suspend this vote, while we work toward consensus. See "Measurement systems No. 4". Maurreen 19:41, 23 July 2005 (UTC)
2. remove the second item and change “permitted” to “recommended” in the first.Christoph Päper 21:07, 23 July 2005 (UTC)
3. Suspend this vote. We're getting there. Neonumbers 11:32, 24 July 2005 (UTC)
Proposed merge
I tried to merge between proposal here on vote and the last version of No. 4 above and arrive at: (−Woodstone 14:53, July 24, 2005 (UTC))
Wikipedia articles are intended for people anywhere in the world. Try to make articles simple to read and translate.
• The primary value should be in whatever unit is appropriate for the context, especially if it is the source value
• The original or other editors are encouraged to help readers by adding conversions to metric and traditional English language units, whichever is (are) not present yet.
• These conversions should be respected by all subsequent editors.
• If a clear source value is available (e.g. from manufacturer's specifications), write the source value first and then the converted value.
• Use digits and unit symbols for the converted value. For example, '100 millimetre (4 in) pipe for 10 miles (16 km)'.
• Converted values should use a similar level of precision as the primary value. For example, "the Moon is 400,000 km (250,000 miles) from Earth", not "(248,548.477 miles)".
• Use standard symbols when using symbols: metre is 'm', kilogram is 'kg', inch is 'in' (not " or ″), foot is 'ft' (not ' or ′)
• Do not append an s for plurals of unit abbreviations. Thus 'kg', 'in', 'yd', 'lb' not 'kgs', 'ins', 'yds', 'lbs'.
• Non-metric units often have more than one version. Be specific. Thus 'US gallon' or 'imperial gallon' rather than just 'gallon'. Similarly, 'nautical mile' or 'statute mile' rather than just 'mile' in aviation, space, sea and some other contexts.
• The reader should see a space between the value and the unit symbol, for example "25 kg" not "25kg".
I like this better. It addresses the problem I pointed out previously. Rl 15:25, 24 July 2005 (UTC)
I like it too. Maurreen 17:09, 24 July 2005 (UTC)
I like it too. If it is in the source, that should be the primary one. Bubba73 02:49, July 25, 2005 (UTC)

#### Comments

There are a few places where metric units are not appropriate. They are totally obvious places, but maybe should be pointed out. Things like The Green Mile (1.6 km), poetry, etc. - Omegatron 19:25, July 23, 2005 (UTC)

1. I'm not sure there is a "clear and present problem". I'm aware of only one case at which removal of metric values was at issue.
2. Any "vote" should ideally state the cut-off point for determining a "winner".
3. Bobblewik -- Why are you doing this when we are working toward consensus above? Maurreen 19:41, 23 July 2005 (UTC)
4. Seems like a good proposal, Bobblewik. The only bit I don't like is the last bullet point, which I would omit. Ultimately the question is whether this wording is better than what we've already got - and the answer is yes. If others disagree, hopefully they'll suggest improvements to this draft, jguk 20:58, 23 July 2005 (UTC)
This vote, in this form, is pure nonsense and an example of why votes don’t work. Only the second (and maybe, partly, the third) of these points is actually disputed. In the first item some, including myself, would prefer “recommeded” instead of “permitted”, but that is just a result of the second being disputed.
“Metric units” furthermore includes those from CGS and MTS systems, which are preferable over FPS units, but not SI (incl. units accepted for use with it like the litre)—in practice that hardly matters, because the units of the most common dimensions (length, are, volume, speed, mass) are valid in all of them.
“US gallon” is ambiguous, by the way. Christoph Päper 21:07, 23 July 2005 (UTC)
I can understand if Bobblewik is getting somewhat impatient. We are getting side-tracked, and many editors join the fray without realizing what the original issue was (a dispute over the first point above). I also see agree with Bobblewik that there is a "clear and present problem". The disagreement was between several experienced and generally well-regarded editors, it was unpleasant for everyone involved, and the dispute was never settled. However, I'm afraid the proposal above is still ambiguous. Some will argue that Metric units are permitted "if editors want them, but we don't want them in this article, so there". Something along the lines of "These conversions should be respected by all subsequent editors." (as others have proposed) will be needed, unfortunately. Maybe we could fix this issue first, then clean up the rest later!? Rl 21:52, 23 July 2005 (UTC)
I agree with handling one issue at a time. In my view, Woodstone's proposalabove does so, and this does not. Maurreen 22:09, 23 July 2005 (UTC)
To answer the requests to remove the second item and change 'permitted' to 'recommended':
• The second item was not there in the first proposal.
• It was added in order to get more support following comments made by Maurreen and others. Regional and multiple non-metric units do exist in articles but I am not aware that they are the subject of confusion or conflict. I chose the term 'non-metric' simply because it covers all units that are not covered by the term 'metric'. That seemed to me to be flexible enough to be non-controversial.
• I would be happy to remove it again if a version without it would get more support.
• The words 'recommend' and generally look good to those that support metric units. But to those opposed to metric units they can be interpreted as a subjective term indicating that they are optional. That was why I used the specific objective term 'permitted'. Furthermore, I think if metric units are recommended, then we would get all sorts of counter-arguments about non-metric units being recommended in certain circumstances. I wanted to keep the guidance concise, easy to read, unambiguous and without caveats.
To answer the point about votes not working: Yes I know that votes are flawed. I don't like them either. I suppose I could have just reverted the anti-metric edits that had been made without consensus. I chose instead to seek consensus. I took most of the existing unambiguous points that had been there for a long time because the main question that I was trying to address was Does the Manual of Style permit removal of metric units?. If people want to act as champions for removing more, that is fine by me but can we get the issue of removal of metric units resolved?
To answer the point about one issue at a time: that is exactly what I am trying to do. The issue is not about editors being motivated to make sensible additions. The issue is about non-metric editors that remove metric edits made by others and claim that action is consistent with the current Manual of Style wording. Because of the mishmash of self contradiction in the current wording, it is not possible to change just one phrase. The rest of the proposed wording is the same as the current wording, or revised in response to requests from people here. Sigh.
To answer Maurreen's point about it not being a clear and present problem: I can assure you that opposition to metric units is not unique to Pan Am 103. You may not encounter it if you do not do much unit editing. If you start adding metric units yourself, you will soon encounter such opposition, reverting, removal and claims of exception. We even have an instance right here on this page where it was suggested that if knots are shown then km/h should not be shown.
As far as suspending the vote is concerned, I would be happy to do that but I suspect that would just prolong the discussion. It is a fairly easy matter to resolve. There is only one completely specified proposal that has been worked through but if anyone wants to completely specify and champion another for consensus please do so.
As far as proposals from others are concerned: I would be happy to consider alternative proposals that address the problem of removal of metric units. However, all I have seen so far is suggested phrases without saying where they will go or what happens to the contradictory phrases. I was trying to be constructive by adding Alternative proposals and Comments. Unfortunately, there is no alternative proposal in theAlternative proposals section, only comments. Can I ask that people take comments out of there and only put specific wording in the Alternative proposals section? Bobblewik 13:24, 24 July 2005 (UTC)

I can see a little better where Bobblewik is coming from. But I'm usually uncomfortable with absolutes. I think Woodstone's proposed merge does a good job of addressing various concerns. Does it work for you? Maurreen 17:09, 24 July 2005 (UTC)

Hmm. It looks as if it would work. Testing it against the question Does the Manual of Style permit removal of metric units? would seem to produce a No. So that is good. However, I have two comments:
• The new clause (the first bullet) introduces a new guideline based on editorial judgement to put the source value second. The fourth bullet means that editors are told to put the source value first. If both units are there, the needs of metric and non-metric readers appear to be satisfied. We have added a new subjective concept that clashes with an objective guideline that was uncontroversial. Readers and editors will no longer be certain which of any values is source data. What problem is this new clause trying to solve?
• The second bullet would convey the same meaning in the shorter form: Conversions to metric and traditional English language units are encouraged.. Bobblewik 17:32, 24 July 2005 (UTC)
I automatically took the new clause to mean what I think it should mean, but I agree that in this regard, Bobblewik's original proposal is less ambiguous. I suggest we just drop the first item. Rl 18:13, 24 July 2005 (UTC)

There is not always a clear "source" value. The proposal therefore differentiates between "source" and "primary" unit. An article may contain data from several sources. Within one article it would not be good to alternate the metric/traditional as primary unit. So an article about the U.S. may have the U.S. style units first, even if some of the data come from a metric source. Articles about many countries may present all data with metric as primary, even though a few of the data elements would have a U.S. style source. However in most cases the source value would be the same that is "appropriate" for the context. The first clause is also meant to allow a third unit in articles about specific subjects that are commonly using other units (chinese, indian). −Woodstone 19:05, July 24, 2005 (UTC)

In my experience, it is always good to know what the source value is – otherwise it is a matter of time until the source value gets changed due to (more "accurate", differently rounded, ...) conversions back from a converted value. I wouldn't mind switching order within an article to indicate that piece of information, but I can see why that might not be popular. In that case, maybe we should ask editors to use <!--inline comments--> to let other editors know what the source value is. Rl 19:19, 24 July 2005 (UTC)
I agree with Woodstone, but I can see Rl's point. Maurreen 07:49, 25 July 2005 (UTC)
So then Woodstone would be saying that, for example, in the basketball article, where the dimensions of the court are specified (which imo shouldn't be in that specific article, but never mind that), either the international dimensions or the NBA dimensions should be converted into the other. The current version specifies international in metric and NBA in U.S. units, because that is how they are specified in their respective rulebooks. I think it would be misleading to convert the source, at least in this case, and in this case at least the sources should remain sources.
I don't know if this case differs from most or if it is the same — basketball is a truly international sport. But if it isn't I think that clearly both are appropriate in their respective places here, in the same article.
On the merge that RI did, I could live with it — I still think division with units should be touched on, and I'm still concerned about units being converted into British traditional units unnecessarily — but for the most part, I'm behind it. Neonumbers 11:10, 25 July 2005 (UTC)
For the record: I didn't do any merging, Woodstone did IIRC. — Keep in mind that we don't need to address everything at once. All the new version needs to be is a clear improvement over the current state. Rl 11:48, 25 July 2005 (UTC)
Yep that's fair. And sorry about the mistake there - I was editing a section and so couldn't scroll up to double check the editor that did it. Neonumbers 12:05, 26 July 2005 (UTC)

In the example above about basketball, there are two separate well defined sources and the actual measures are not necessarily the same (I don't know anything about basketball). In such cases both could be cited separately and the conversion of one may be different from the other source value. My guess would be that such examples are relatively rare and need not explicitly be covered in the guideline.

For the division question, the rule might be stated as:

• if a division is present between units, the precedence among any operators between following units should be clarified by using parentheses.

Woodstone 11:38, July 25, 2005 (UTC)

I disagree strongly with your comments above; the original measurement should come first, and it doesn't matter if sometimes that uses metric units and sometimes English units. TThe reasons are that the original measurement often gives you the best idea of the precision of the measurement, and it is a check to make sure that the conversions are done properly (and tells you which one is most likely correct if there is a conversion error). There are, of course, times when it is acceptable to have a table with metric units in one column and English in the other, and one might be primary in some cases and the other in other cases. I have no problem with that.
Note that it is the units used in originally making the measurement, or specified in the rules (e.g. the basketball three-point lines example) or laws or design drawings, that really matters. Whatever we as editors use as our sources can sometimes provide evidence of that original measurement. In many cases there will be minor discrepancies in various sources, but that can often be traced to conversion problems rather than being any real difference; only rarely will there be a need to note different values from different sources in the article.
Caveat: specifying in some sporting event rules that a distance is 3.048 m doesn't mean that the original isn't 10 feet, nor does specifying in United States Code annotations that a nickel is 77.16 grains change the fact that these have been designed as 5.00 grams ever since they were introduced 139 years ago.
There are also many measurements where identifying an original measurement doesn't matter, and the units can appear in either order. Reasons include just being a rough approximation in either unit, being a quantity repeatedly measured in both units, or actually being known more precisely than what is stated in the Wikipedia article.
In other words, this also involves interpreting what you read in your sources. Perhaps other measurements in that source can help you in making that interpretation. For example, there may be a systemic error in that source, with numbers expressed only in feet with four significant digits, but actually being conversions from values in meters using a conversion factor of 3.3 ft = 1 m.
I have a quibble with your statement above, that an article "may have the U.S. style units first, even if some of the data come from a metric source". That "metric source" may well be in the United States, of course. Just a warning to avoid the trap of using "articles dealing with the United States" or something like that as part of our criteria. It is more complicated than that. Gene Nygaard 12:50, 25 July 2005 (UTC)
To emphasize one aspect alluded to by Gene: Dimensions in legal documents are exact even if no significant 0s are mentioned after the whole units. Any conversion to an equivalent precision would look like an excessive number of digits to the uninformed. If the stated whole units are converted to the same number of significant digits, then the result would only be a rough approximation of the exact number. If the number of significant digits is increased to the precision with which such a dimension can be measured, the conversion itself looks ridiculous. For example, 12 nautical miles (22.22400 km), where the conversion is given to the centimetre level because that is the precision of modern GPS units relative to a fixed base unit. Even conversion to the exact metre level in the unit's definition (1 nautical mile = 1852 m exactly, thus 22.224 km) looks suspicious. I prefer to only perform the whole digits conversion (22 km) and state somewhere in the article that the primary units are exact legal definitions whereas the secondary units are only rough approximations. However, I'm not sure if these sitiuations should be mentioned in the Manual of Style. — Joe Kress 23:45, 25 July 2005 (UTC)
Meanwhile, back at the ranch, the very pretty state quickfacts tables all consistently give the states' areas and population densities in the utterly meaningless (to the vast majority of American readers) metric system with no mention of standard units. Tomer TALK 19:56, July 25, 2005 (UTC)
And that's relevant how? I trust if you were bold and added imperial units, no metric zealot would revert you. Folks, we are getting side-tracked again. These are not the issues we set out to fix. Focus, dagnabbit! Rl 20:31, 25 July 2005 (UTC)
It doesn't take a "metric zealot"; members of various Wikipedia projects (see Wikipedia:WikiProject) are often quite protective of what they come up with in the way of infoboxes and the like. That's one reason we need sensible and fairly clear guidelines here in the MoS, so that these guidelines can be pointed out when the discussions come up in those projects, and various discussions don't have to be started from scratch each time.
That basketball example is very rare in my opinion, and the source should always go first (except in comparison tables). Reasons echo Gene's. So long as the source always goes first. I can't think of any exceptions.
I could specify my thoughts about division (parentheses was the least of my concerns) but I'll refrain from doing that — I'll bring that up after we put this in the manual, and we can discuss its existence or non-existence then. We'll just get this text replaced first... Neonumbers 12:14, 26 July 2005 (UTC)

### Seventh attempt at a revised wording for the 'Units' section

Here is a seventh attempt at a revised wording for the 'Units' section. We do not have a conflict in Wikipedia articles related to what editors add, we have a conflict related to what editors remove. So this version does not address addition, it only addresses removal.

Wikipedia articles are intended for people anywhere in the world. Try to make articles simple to read and translate.

• If a metric unit is added, it should be accepted by others.
• If a traditional English language unit is added, it should be accepted by others.
• If editors cannot agree about the sequence of units, put the source value first and the converted value second.
• Use digits and unit symbols for the converted value. For example, '100 millimetre (4 in) pipe for 10 miles (16 km)'.
• Converted values should use a similar level of precision as the source value. For example, "the Moon is 400,000 km (250,000 miles) from Earth", not "(248,548.477 miles)".
• Use standard symbols when using symbols: metre is 'm', kilogram is 'kg', inch is 'in' (not " or ″), foot is 'ft' (not ' or ′)
• Do not append an s for plurals of unit abbreviations. Thus 'kg', 'in', 'yd', 'lb' not 'kgs', 'ins', 'yds', 'lbs'.
• Non-metric units often have more than one version. Be specific. Thus 'US gallon' or 'imperial gallon' rather than just 'gallon'. Similarly, 'nautical mile' or 'statute mile' rather than just 'mile' in aviation, space, sea and some other contexts.
• The reader should see a space between the value and the unit symbol, for example "25 kg" not "25kg".

I hope that addresses the problem without creating new ones and deals with the many good points raised. Bobblewik 13:07, 26 July 2005 (UTC)

That works for me. Thank you. Maurreen 16:32, 26 July 2005 (UTC)
If the editors can agree (or if there is only one), don't we have a suggestion what to put first (source value)? – What, nitpicking, me? Rl 17:12, 26 July 2005 (UTC)
Sometimes the context might determine which type of unit should be primary. And there could be multiple sources for the same thing. Maurreen 17:20, 26 July 2005 (UTC)
Sometimes metric units are just not useful, and may even confuse, so we shouldn't have a requirement to keep metric in there. As far as traditional English units are concerned - what if I find five of them to describe the same thing - that'd be fun - no-one would be allowed to remove them afterwards! And I could go on. I'm afraid, although well-intentioned, the proposal isn't sensible.
Couldn't we simplify it - and deal with the original problem that gave rise to this discussion by "encouraging editors to provide conversions of measurements where they may be useful to our readers, bearing in mind that we have an international readership"? jguk 17:36, 26 July 2005 (UTC)
You are raising good points. Pretty much any conceivable wording will to some degree rely on people using common sense when interpreting it. Unfortunately, we came here because of a large disagreement over exactly such a common sense interpretation. Maybe we should try to get the spirit across, because the letter we can't get perfectly right anyway. However, I'd rather take the existing proposal before everyone gets tired of this and gives up. We do have an important issue to address. Rl 18:07, 26 July 2005 (UTC)

It seems like the last 6 bullets in the 7th proposal are not contested anymore. So we can focus on the first 3 (Bobblewik) or 4 (Woodstone). The version of Bobblewik does not address the concept of "appropriateness" for the context brought up explicitly first by Neomumbers. It also is not clear on an exotic primary unit, specific for a subject field. The problem of endless "traditional units" brought up by Jguk could be addressed by specifying that "one" metric or traditional conversion is allowed. Maurreen (and me) are not convinced that a "source" unit as always definable. In my view the "appropriate" unit is more important than the "source" unit. For example an editor may use data from a US government publication in an article it may seem like a source value, but in reality it is most likely a converion already. So here an eighth proposal for the initial part:

• The primary value should be in whatever unit is appropriate for the context
• If a clear source value is available its unit may be used as primary instead
• Editors are encouraged to add conversions to one metric and one traditional English language unit, whichever style is (are) not present yet
• These conversions should be respected by all subsequent editors

Woodstone 20:50, July 26, 2005 (UTC)

Bullets 4 and 5 of the original proposal are in contradiction. It should read instead:
Wikipedia articles are intended for people anywhere in the world. Try to make articles simple to read and translate.
• If a metric unit is added, it should be accepted by others.
• If a traditional English language unit is added, it should be accepted by others.
• If editors cannot agree about the sequence of units, put the source value first and the converted value second.
• Use digits and unit symbols for the converted value. For example, "100 millimetre (4 in) pipe for 10 miles (16 km)".
• Converted values should use a similar level of precision as the source value. For example, "the Moon is 400,000 km (250,000 mi) from Earth", not "(248,548.477 mi)".
• Use standard symbols when using symbols: metre is 'm', kilogram is 'kg', inch is 'in' (not " or ″), foot is 'ft' (not ' or ′)
• Do not append an s for plurals of unit abbreviations. Thus 'kg', 'in', 'yd', 'lb', not 'kgs', 'ins', 'yds', 'lbs'.
• Non-metric units often have more than one version. Be specific. Thus 'US gallon' or 'imperial gallon' rather than just 'gallon'. Similarly, 'nautical mile' or 'statute mile' rather than just 'mile' in aviation, space, sea and some other contexts.
• The reader should see a space between the value and the unit symbol, for example "25 kg" not "25kg".
Secondarily, the mile example is a problem, since the "statute mile" is not the same as the "international mile". A statute mile is a U.S. Survey mile (approximately 1.609 347 218 694 44 km) whereas a mile is 1.609 344 km. See the NIST Special Publication 811 - Guide for the Use of the International System of Units (SI) (1995), pages 43-44.
In fact, I heartily recommend several of the NIST SP 811 "Check List for Reviewing Manuscripts" recommendations be incorporated:
Wikipedia articles are intended for people anywhere in the world. Try to make articles simple to read and translate.
• The primary value should be in whatever unit is appropriate for the context.
• If a clear source value is available its unit may be used as primary instead.
• Editors are encouraged to add conversions to one metric (SI) and one traditional English (SAE or Imperial) unit, whichever style is (are) not present yet.
• These conversions should be respected by all subsequent editors.
• Non-metric units often have more than one version. Be specific. Thus 'US gallon' or 'imperial gallon' rather than just 'gallon'. Similarly, 'nautical mile', 'statute mile' or 'international mile' rather than just 'mile' in aviation, space, sea and some other contexts.
• If editors cannot agree about the sequence of units, put the source value first and the converted value second.
• Use digits and unit symbols for the converted value. For example, "100 millimetre (4 in) pipe for 10 miles (16 km)".
• Converted values should use a similar level of precision as the source value. For example, "the Moon is 400 Mm (250 000 mi) from Earth", not "(248 548.477 mi)".
• Use standard symbols when using symbols: metre is 'm', kilogram is 'kg', second is 's', inch is 'in' (not " or ″), foot is 'ft' (not ' or ′), metre per second is 'm/s', not 'mps', and so on.
• Do not append an s for plurals of unit symbols or abbreviations. Thus 'kg', 'in', 'yd', 'lb', not 'kgs', 'ins', 'yds', 'lbs'.
• The reader should see a space (ideally a non-breaking space, &nbsp;) between the value and the unit symbol, even when the value is used in an adjectival sense, for example "25 kg" not "25kg" or "25-kg". The only exceptions are the superscript units of plane angle (degree, minute and second of arc); thus "an angle of 2°3'" but not "an angle of 2 ° 3 '". If the spelled-out name of a unit is used, the normal rules of English are applied: "a roll of 35-millimetre film".
• Information is not mixed with unit symbols (or names). For example, the form "the water content is 20 mL/kg" is used and not "20 mL H2O/kg" or "20 mL of water/kg".
• Make it clear to which unit symbol a numerical value belongs and which mathematical operation applies to the value of a quantity. For example, "35 cm × 48 cm" but not "35 × 48 cm", "1 MHz to 10 MHz" or "(1 to 10) MHz" but not "1 MHz—10 MHz" or "1 to 10 MHz".
• Unit symbols and unit names are not mixed and mathematical operations are not applied to unit names. For example, only forms such as "kg/m³", "kg·m⁻³", or "kilogram per cubic metre" are used and not forms such as "kilogram/m³", "kg/cubic metre", "kilogram/cubic metre", "kg per m³", or "kilogram per metre³".
• Values of quantities are expressed in acceptable units using Arabic numerals and the symbols for the units. For example, "m = 5 kg" but not "m = five kilograms" or "m = five kg".
• The digits of numerical values having more than four digits on either side of the decimal marker (a period in English) are separated into groups of three using a thin, fixed space (&thinsp;, but some browsers don't treat it right; so use &nbsp; instead) counting from both the left and right of the decimal marker. For example, "15 739.012 53". Commas are not used to separate digits into groups of three.
Urhixidur 21:19, 2005 July 26 (UTC)
All editors think their edits are appropriate for context. Metric units were considered inappropriate in Pan Am 103. Metric units were considered inappropriate in nautical articles (see comment above). Metric units were considered inappropriate in GT90. Metric units were considered inappropriate in 'US articles'. Instead of permitting editors to remove metric units, we will be permitting them to put metric source data into second place. That is not progress, it is merely changing the battleground.
Unit sequence is not a problem in Wikipedia. No conflict. No confusion.
Multiple units are not a problem in Wikipedia. In fact, they are part of the solution in automobile (PS, hp, kW), nautical and aviation articles (knots, mph, km/h). I have also seen articles with acre-feet, US gallons and litres. I have seen articles with stones, pounds and kilograms. I have seen articles with acres, square miles and square kilometres. No conflict. No confusion.
Without a problem of conflict or confusion, we do not need a solution. A dispute between editors that cannot agree about units being appropriate cannot be solved by creating more ambiguity and judgement calls in guidance. Can we just leave the issue of unit sequence and multiple units alone. Please? Bobblewik 23:10, 26 July 2005 (UTC)
No, Urhixidur, you are imagining problems which do not exist with miles. A "statute mile" is not the same thing as a "U.S. Survey mile". Your mistatements in that regard, or at least the most obvious one, in the mile article was also corrected a long time ago.
Yes, the U.S. Survey mile is a "statute mile", the latter being a broader term. But so is any other mile of 5,280 feet, including the one based on the 1959 international redefinition of a yard.
What do you suppose that "statute" refers to?
Note specifically that those two specific types of miles (equal to exactly 1.609344 km or exactly 1.609344/0.999998 km) are not primarily defined by any United States statute. The 1959 redefinition of the mile (and the retention of the older definition for survey purposes only) was implemented by regulatory action by the experts in the field of metrology, in what was then the National Bureau of Standards, who had been delegated the power to make those decisions. Not by statute, which refers to a law enacted by the legislature. Furthermore, you can readily find evidence from throughout the world that the term "statute mile" is not specific to the United States and did not originate in the United States. So the adjective "statute" in the term "statute mile" does not refer to any United States statute.
The statute referred to in the name of these miles is a statute of 11 or 13 or some year in that range of the reign of Elizabeth I of England, defining the mile as 5,280 feet for limited purposes in a limited geographical area around London. Gene Nygaard 03:42, 27 July 2005 (UTC)

I'd like to throw out some comments. Since I believe that the true test is in the more difficult cases, I'll bring up several things that don't necessarily belong in the guidelines here, but which should be considered in coming up with these guidelines.

1. It isn't just English to metric and metric to English. The considerations are often the same in converting between two "metric" units (e.g., angstroms to nanometers, kilograms-force aka kiloponds to newtons) and in converting between two English units (e.g., water flow from U.S. gallons per second to cubic feet per second), or in converting something that is in neither system to English or metric or both (parsecs to miles or kilometers, shaku to feet or meters).
2. The phrase "traditional English language unit" doesn't work. The "kilogram" is an "English language" unit; in modern Quebec, a "pied" is no different from an English foot, other than not being "English language". Just use English unit with a link to that article which somebody (it wasn't me) finally had the good sense to start.
3. There might be rare occasions where more than three units could legitimately be used. For example, there are at least four different units currently used for wind speeds in weather reports: statute miles per hour, kilometers per hour, meters per second, and knots. In addition, feet per second are often used in science textbook problems, wind tunnel calculations, as a converions of measurements originally expressed in meters per second, etc. Then, fortunately mostly historically, there is also the Beaufort scale.
4. The cgs and mts systems certainly are not "preferrable over FPS units" as Christoph Päper claims.
• In fact, I'd say that these present one of the few cases where it would be acceptable to throw out the units used in the source measurement (in the sense of the source used by a Wikipedia editor) or the original units in which a measurement was made, simply replacing them with SI units.
5. There are many other non-SI metric units which are more likely to be encountered, and which cause more problems, than cgs and mts units. For example:
6. Other units still in use, and often including or included in conversions, aren't really either metric units or English units:
7. There is little ambiguity in U.S. gallons; hardly anybody ever refers to or uses the U.S. dry gallon under that name. There can, however, be ambiguity in U.S. pints or quarts, where the dry pints and quarts are still used.
8. Conversions between different English units or between different metric units often present he same problems as conversions between English and metric units. You can still have the same problems with the precision of the results, for example.
9. Often, there are choices in what units to use in conversions. See, for example, the discussion about "rate of climb" in m/min or m/s at Wikipedia talk:WikiProject Aircraft#Rate of climb.
10. Precision of results: the general philosophy ought to be that those who ignore one set of units get essentially the same information as those who ignore another set of units. The conversions are just as objectionable if they are too imprecise as they are when they are too precise. Note that there will almost always be a couple of possibilities, a little more precise or a little less precise. Note also that the actual precision of the stated measurement often needs to be determined by whatever we know about how precisely those measurements are normally made, because final zeros before the decimal point may or may not be significant, and because final zeros after the decimal point may be omitted even if they are significant.
11. I agree with the point someone made that we should make clear that it is acceptable for editors to add information using either metric or English units, and not imply that the burden is on them to add the conversions (in any case, making the conversions is often better left to those more experienced in making them).
12. Significant continuing use of particular units of measure today, in at least some particular field of activity or some particular geographical location, would be a useful criterion in determining whether or not it is acceptable to add a conversion to those units.
13. Continuing use of non-SI units in any particular field of activity should not be sufficient to preclude conversion to SI units. The fact that SI is an interdisciplinary system is as important as the fact that it is an international system.
14. Yes, centimeters and grams are part of SI as well as part of cgs systems. However, measurements such as 6.652 x 10-25 cm2 are not SI, but clearly a holdover from cgs days.
15. There will be situations where the use of other non-English customary units are appropriate. The shaku is handy in explaining the size of a standard Go board, for example. The rule should be that whenever these units are used, they should include a conversion to English units or metric units or both.
16. If it were only U.S. units, we'd never have any long tons force, but there are dozens of Wikipedia articles using them. Many people do not realize that we do use long tons in the U.S. for limited purposes (and not as much as we used to, having replaced them with metric tons in some uses). But we never use long tons force. See, e.g., British Rail Class 55.
17. When the dirct "source" of the Wikipedia wording is a dump of the 1911 Encyclopædia Britannica or some other old public domain source into the article, it ought to be acceptable to simply replace obsolete units used there (maybe drachms for drugs, pecks for seeding instructions, or ergs in a scientific article, or something like that) with units still in general use today.
18. When should it be acceptable to limit a particular block of text to only one set of units?
• Some formulas are unit dependent, and at other times there are worked out examples showing how a formula works using particular units. The way to deal with this is not to put in conversions with each unit used. Sometimes these articles already include a more general formula or parallel example in other units, and it would often be acceptable to add that if it isn't already there.
19. Sometimes the whole question can be avoided by rewording. If something is not unit-dependent, don't use the word "calories" as a substitute for the quantity being measured (e.g., food energy). If a dimensionless ratio is the important factor, it can often be expressed in a way that avoids specific units for the quantities being compared.

There isn't much here that needs to be specifically included in our guidelines, but lots of things to be considered in making those guidelines. If nothing else, it might keep us from making a hard and fast rule in some cases where it would be sensible in 99% of the cases, but would fail in the other 1%. Gene Nygaard 13:24, 27 July 2005 (UTC)

### Simplifying this: proposal 9?

The original concern that started this discussion was the removal of conversions. Maybe we should focus on that first.

1. Can we agree on removing this: "It may be helpful to readers to offer equivalents, but this should not be done if it reduces the flow of a sentence or otherwise interferes with the quality of the writing."
2. And can we replace it along these lines: "Conversions appropriate to the context should not be removed." Maurreen 15:01, 27 July 2005 (UTC)
Heh. If you want it simple, how about simply undoing this edit? The text wasn't all that bad just a few months ago. Rl 15:18, 27 July 2005 (UTC)
Maurreen, the problem is that some editors claim that metric units are not appropriate to the context. Conflict and confusion has been caused because some editors have claimed that metric units are not appropriate for the following contexts:
• nautical articles
• aviation articles
• US articles
Editors on both sides of a dispute claim that their edits are appropriate to the context. The phrase is as subjective as interferes with the quality of the writing.
Theoretical problems that do not cause conflict or confusion include:
• inappropriate conversions (poetry, figures of speech, object names)
• multiple units
• inappropriate unit sequence
• non-metric units unfamiliar to English language speakers (I propose going back to the term 'non-metric units')
None of the proposals that I made address those theoretical problems. Everything is allowed unless disputed. Addition or removal of units is not constrained unless disputed. All sequences are permitted unless disputed. The proposals were only made to address the problem of disputed removals that claim to be consistent with the current text of the Manual of Style. We get so close to fixing the problem but then we move right away by reintroducing ambiguity and subjectivity. If we can't agree on any of those proposals then perhaps RI's proposal is the way to go. I am frustrated that we have discussed non-problems in such depth. There was no consensus or debate about the anti-metric edits that are the real problem. Bobblewik 16:28, 27 July 2005 (UTC)

Then how about "Conversions should generally not be removed"? Maurreen 16:38, 27 July 2005 (UTC)

### Tenth attempt at a revised wording for the 'Units' section

I still would prefer to be more specific in line with previous proposals. However, I am keen to end talking and get action. This version now includes Maurreen's wording. The proposal is to replace the entire 'Units' section with:

Wikipedia articles are intended for people anywhere in the world. Try to make articles simple to read and translate.

• Conversions should generally not be removed.
• If editors cannot agree about the sequence of units, put the source value first and the converted value second.
• Use digits and unit symbols for the converted value. For example, '100 millimetre (4 in) pipe for 10 miles (16 km)'.
• Converted values should use a similar level of precision as the source value. For example, "the Moon is 400,000 km (250,000 mi) from Earth", not "(248,548.477 mi)".
• Use standard symbols when using symbols: metre is 'm', kilogram is 'kg', inch is 'in' (not " or ″), foot is 'ft' (not ' or ′)
• Do not append an s for plurals of unit abbreviations. Thus 'kg', 'in', 'yd', 'lb' not 'kgs', 'ins', 'yds', 'lbs'.
• Non-metric units often have more than one version. Be specific. Thus 'US gallon' or 'imperial gallon' rather than just 'gallon'. Similarly, 'nautical mile' or 'statute mile' rather than just 'mile' in aviation, space, sea and some other contexts.
• The reader should see a space between the value and the unit symbol, for example "25 kg" not "25kg".

#### Vote

Vote for

1. Bobblewik 17:06, 27 July 2005 (UTC)
2. Whatever. If I am not enthusiastic about this proposal, it is certainly not for lack of trying by everyone involved. I am impressed by all the hard work that has gone into this, but I think we should bring it to an end before we are all worn out. Therefore I am willing to vote for any proposal that looks like an improvement. We can still fix it later. Rl 20:22, 27 July 2005 (UTC)
3. For, but some exceptions must be noted, as jguk says (e.g. 3'44"). Also, although this is a different topic, he mentions writing out the words to at least ten. I tend to go by the Chicago Manual of Style which basically says that if it is a measurement, use digits (except not at the beginning of a sentence). If it is something you count, then write it out in words if it is under 100, otherwise use digits. So the "truck has four tires" but "the truck weighs 4 tons". Bubba73 20:34, July 27, 2005 (UTC)
4. For, but it still needs work: 1) Bullet 3 needs to be applied to bullet 4. 2) Bullet 7 should avoid "statute", which, as Gene Nygaard has explained, is ambiguous. "International mile" isn't (frankly, I doubt there's ever a real risk of confusion between nautical miles and the "land mile"). 3) Bullet 8 should mention the degree/minute/second (of arc) exception.
No, it should be "statute mile", the normal terminology, and not "international mile", a term known only to measurement freaks. There is no serious ambiguity; the modern definition is 1.609344 km. It is only in the limited, specific context of United States land surveys that the measurements have not been converted to the old standard. The difference of two parts per million will never matter if you have fewer than six significant digits in a emasurement, which takes care most of them used in Wikipedia. If it has more digits than that, and it is in U.S. Survey miles, that fact can be noted.
How can you "doubt there's ever a real risk of confusion between nautical miles and the 'land mile'"? See a recent change I made in Iwo Jima, for example. I've made other, similar corrections several times in the past. Or look at some of the published reports on the altitude of the space station above the Earth's surface; it depends on whether the miles come from NASA engineers directly, or if the NASA public affairs office has gotten its fingers in there—and we often do not know which it is, because neither are particularly diligent about identifying the miles used.
Or do a Google search (and do a manual search of lots of books and other printed reference works as well) for
• Shackleton "156 km"      142 hits
• Shackleton "155 km"       21 hits
then go look at the edit history of the Ernest Shackleton article here on Wikipedia, and search for that particular number in any version from 10 June 2003 until 24 April 2005, a period of nearly two years. Hint: how many minutes of arc are there from 88°23′ S—the southernmost latitude reached, as stated right there in the article—to the South Pole at 90°0′ S? Can you do the sexagesimal arithmetic, then convert it to minutes of arc? Do you know the significance of the "97 miles" figure which appeared before 10 June 2003 and at various times since in this article? You do also know the connection between 97 miles and 156 km, don't you?
It would make more sense to say that we should not use liters (even if you spell them litres) because they are ambiguous, than it does to say we should not use statute miles because they are ambiguous. After all, the relative error in using the current definition of a liter for a 1958 liter is 14 times as great as the relative error in using the current definition of a land mile for a 1958 U.S. land mile, or a U.S. Survey mile. Gene Nygaard 02:19, 28 July 2005 (UTC)
So we're stuck with using "statute mile" because international mile is obscure and the nautical mile confusion is frequent? Sad, but apparently true. The examples you give are frightening. As for the litre, there is no ambiguity, just a change over time (somewhat like the calendar problems we sometimes have with the Gregorian reform), whereas the statute mile is just plain ambiguous, having no official (in the metrological sense) existence. I had originally come to the equation U.S. Survey mile = Statute mile because of NIST SP 811, which states (p. 44) « 8 fur = 1 U.S. survey mile (also called ‘‘statute mile’’) » without explaining that "statute mile" is also applicable to the international mile. I was also influenced by having seen "statute mile" only on U.S. road maps, which are obviously using U.S. Survey data.
Urhixidur 13:00, 2005 July 28 (UTC)
5. Generally for...
• I'd add "The same order should be used throughout the article" to the end of point 2. This is so in a single article its always imperial (metric) or metric (imperial), not a mix of the two.
• I'd add guidelines about the order, possibly separate from the explicit instructions along the lines of
• "for geographical or historical articles, the primary units should be those in use at that place at that time (e.g. an article about Great Britain should use British units first, and article about modern France should use metric units first).
• "articles about technology, products or projects the primary units used should be those used by those responsible for the design, etc. (e.g. if a car was desgined in metric units the metric units should come first, if a project relates to "fish that live between 200 and 600ft below the ocean surface" then the imperial units should come first).
• "sports articles should use the units used in the rules of the sport (e.g. a soccer pitch is defined in imperial, but a rugby pitch defined in metres. If both are used then use the order that the rules do).
• "Use the order used by the primary source(s) for the article, where this is clear and consistent. If it isn't, use the order used by the first primary contributor (like the British English/US English differences)
• I don't like the don't pluralise unit abbreviations point. If and when an abbreviation should be pluralised or not depends largely on the abbreviation in question - e.g. I'd expect to see "600 kg" / "600 yds" / either "600 lb" or "600 lbs" - but the article should be consistent on one or the other.
• For the different versions, I'd say disambiguate on first usage, be consistent after that.
• I'd add "If including a conversion would disrupt the flow, consider using a footnote instead".
• I'd add "for dimensions, include the conversion for all the dimensions at the end, e.g. 6 miles × 14 miles (9.6 km × 22.5 km)" Thryduulf 14:14, 29 July 2005 (UTC)
Your first point is a "hobgoblin of little minds" [Oliver Wendell Holmes, Sr.]; a "foolish consistency" that throws away useful information about the precision of the measurement, and the one more likely to be correct in the case of a conversion error.
No unit symbols should have a language-dependent change in the plural, even though some are fairly often used that way. The invariant ones are also in general use, and it is good for us to use a consistent, easily determined style.
When only one of a number of appearances of a particular unit is disambiguated, it is often difficult to determine whether that one was identified because it was an exception to the general usage, or because it is exemplary of that general usage. In most cases, ambiguous units should be identified in each use; in exceptional cases, an explicit statement that this is the definition of that unit always used in a particular article would work. Gene Nygaard 14:34, 29 July 2005 (UTC)
That first point of Thryduulf's, refer to my example about basketball where FIBA specifies dimensions in metric and NBA does in imperial. It would be inaccurate to state metric as primary for NBA. Neonumbers 11:56, 30 July 2005 (UTC)

Vote against

1. First two sentences good. Rest mostly bad. First bullet point: It's easy to put silly conversions on, and of course these should be removed. Second bullet point assumes a single source, which very often will not be true. Third bullet point contradicts the normal rule in writing that numbers from one to at least ten are written out in full. Fourth bullet point is fine. Fifth bullet point is imprecise - there are many duplicate symbols, also John Cage did not write 3 minutes 44 seconds, he wrote 3'44''. Fifth bullet point is nearly there buy "and some other contexts" is imprecise. Sixth bullet point, I disagree with - aesthetically 25kg is better, jguk 17:53, 27 July 2005 (UTC)
I will happily go back to the fifth version . You description of that was: Seems like a good proposal, Bobblewik. The only bit I don't like is the last bullet point, which I would omit. Ultimately the question is whether this wording is better than what we've already got - and the answer is yes. If others disagree, hopefully they'll suggest improvements to this draft, jguk 20:58, 23 July 2005 (UTC). The 5th and 10th versions are identical in bullets 4, 5, 6, 7 and 8(last). These bullets are based on the current Manual of Style. But if you don't like them, I will take them out. Bullet 1 does not stop removal of conversions, it only ends Manual of Style support for disputed removal. Bullet 2: I don't think editors will mistake the meaning but I would be happy to change it to source values and to change converted value to the values that you have obtained by conversion. Bullet 3: this is in line with current practice but I would be happy to remove it too. Sigh. Bobblewik 18:39, 27 July 2005 (UTC)
How about Where digits are used, use unit symbols for the converted value, followed by an example where digits are actually used, i.e. with big numbers or when not in prose. Neonumbers 10:26, 31 July 2005 (UTC)

Comments

Does this comment belong in vote for? Bobblewik 18:39, 27 July 2005 (UTC)
I support the change, but prefer not to call my support a vote. Maurreen (talk) 02:58, 28 July 2005 (UTC)
• Me, I like Woodstone's way of the first two bullets that we wrote about in the seventh attempt better. You can call me distrusting, but I'm not sure I trust people to keep sensible with their conversions. But I don't want to be the one that holds this back another week. To be honest, I'm a bit worn out from this. Can we please discuss conversions and appropriate/source units after we substitute the text, along with division? We've sorted everything else. Everything else is good. I abstain from voting. Neonumbers 12:21, 29 July 2005 (UTC)
• I've just started looking at this page and am having problems following the history of the discussion, so forgive me if some of this has been addressed or I'm stepping on any toes. I am in favor of the list above with the changes listed below. Since I have not been immersed in this discussion, I think my comments should be indicative of confusion a new user might still have when reading the MoS for the first time.
• Change 3rd bullet (italics = new): Spell out units in text. Use digits and unit symbols for any converted value or for values in tables. For example, '100 millimetre (4 in) pipe for 10 miles (16 km)'.
• Add to end of 8th bullet: To ensure that the value and the unit symbol are displayed on the same line, editors should use a non-breaking space character rather than a standard space: type 25&nbsp;kg rather than 25 kg. Avoid entering the character directly, even when possible, for some browsers substitute all instances of it with the normal, breaking space.
• Add a bullet: When the unit is part of a quote it should not be changed. If an editor wishes to provide a conversion, it should be added in brackets (rather than parentheses) after the unit within the quote.
• Add to 5th bullet (italics = new): ... when using symbols and do not use trailing periods. metre is ...
• Fix that the fourth bullet violates the suggestion of the third bullet.
• Use consistent labels for examples. In the list above, one bullet uses "for example", one uses "thus", and one doesn't have a lead-in to the examples.
NB, the language to be added to the 8th bullet, regarding non-breaking spaces, has various markup in it, so should be copied from the edit box of this page or the existing MoS page — where I copied it from — if this comment is accepted. Chuck 21:38, 2 August 2005 (UTC)