# Talk:ISO 31-11

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## Unicode UP TACK versus PERPENDICULAR

Okay, now we are getting really deep into the Unicode standard, but shouldn't the perpendicular operator be ⟂ (U+27C2 PERPENDICULAR) instead of ⏊ (U+23CA DENTISTRY SYMBOL LIGHT UP AND HORIZONTAL, as currently used in the article)? --Abdull 22:15, 28 May 2006 (UTC)

Well spotted! My mistake. The character I actually wanted to use was ⊥ (U+22A5 UP TACK). I took a wrong turn in the code charts, was heading for APL symbols, but actually ended up in Japanese dendistry symbols ... a likely peril in the age of mega character sets. UP TACK is widely supported in existing fonts and seems the appropriate Unicode 4.0 character for the perpendicular symbol to me. A dedicated ⟂ (U+27C2 PERPENDICULAR) was added only quite recently (Unicode 4.1) and I'm not fully convinced yet that there was a good case to disambiguate between the two. The glyphs for UP TACK and PERPENDICULAR are for all practical purposes identical, and the difference between a constant and an operator only matters in TeX-style math-rendering implementations that try to automatically insert whitespace near operators, which is irrelevant for HTML, Wikipedia, etc. So I prefer to use UP TACK instead of PERPENDICULAR for the moment, because the latter is not yet widely implemented in fonts. Markus Kuhn 19:19, 29 May 2006 (UTC)

## Angle brackets

I'm seeing ? where I think other character should be. In the mathematical symbols table it has the line:

⟨⟩ |?a+b?c | ac+bc, angle brackets

<> |<a+b>c | ac+bc, angle brackets

Or am I missing something.

The font your particular browser uses probably still lacks glyphs for the two characters U+27E8 (MATHEMATICAL LEFT ANGLE BRACKET) and U+27E9 (MATHEMATICAL RIGHT ANGLE BRACKET). The angle brackets have, unfortunately, a somewhat confused history in Unicode. They were for a while mistaken to be CJK wide characters, and disambiguated from these (unnecessarily) rather late. Markus Kuhn 22:01, 3 July 2006 (UTC)
It does seem to be a font issue, but I wonder if many people will have the same issue. I'm on Mac OS X 10.4.6 and though I have all of the standard internet/web fonts installed (and then some) I still don't have any that have a glyph for this character. I wonder if a note should be added to show what it should roughly look like using another more commonly existing glyph (like simply the greater than less than charaacter glyphs like I used above). I don't think the characters in the main text should be changed, but just suggest a note be added, since I don't imagine I'm the only one to encounter this problem. As the fonts improve and proliferate, the note could then be taken away. --Cplot 23:13, 3 July 2006 (UTC)

BTW, I have the same problem with the perpindicular glyph in the comment above (though the dentistry glyph displays fine, so maybe a similar not should be added there if the peripindicular character is correct).

Please report what exact browser and font you are using, and I'll be happy to investigate and report the problem upstream. I'd rather see this fixed in the font and not in the article. Markus Kuhn 08:41, 5 July 2006 (UTC)

## Note on Unicode repertoire used

I'm sorry you felt those notes were defacement. I felt I was improving the article, which btw is quite helpful. I fully support your goals for this article, but feel some explicit statements to that effect would be helpful. I'm running another leading edge operating system with X11 installed and I'm missing glyphs for these characters. It took me some time to figure out what was going on and I felt that, rather than make everyone else go through that same process, I'd provide the answers I gleaned for everyone else in notes to the table.
I've sinced moved those note to footnotes so they won't clutter the table. Let me explain my reasons. If we want this to be leading edge, then we need to put the correct unicode character in the text. However, since it's also an enyclopedia article, the general reader should learn the basics about the ISO31-11 standard. If an important glyph is missing then they'll go away scratching their heads. Apparantly neither of us have a perpindicular glyph, so it's counterproductive in trying to push the edge to simply substitute a similar character without noting that fact. It makes everyone reading the article complacent with their font support even when they're missing support for an important unicode character. The characters are important in many more places than just TeX. They're meant to convey meaning: both for machine processing and human readable form in a variety of places. Substituting a character with a similar looking glyph may convey the meaning in human readable form, but it destorys the meaning in terms of machine processing. Finally, on the angle brackets, I think some substitute is necessary. I've checked across Firefox and Safari (a KHTML descendant) and neither displays these characters correctly. As I mentioned I have a standard X11 enviornment installed, so that doesn't help the situation. I also have the standard "web" fonts installed, which is all we should count on a site like Wikipedia. It is probably these fonts that need support added for the perpindicular and the angle brackets.
So to further our worthy goals, I've added these notes again as footnotes. I've also added a requesti for readers to contact their vendors to imrpove support for these characters. I think this furthers our goals.
One last point. i think it might be helpful to list the character references for these unicode characters. In the notes I added I used the character references in my markup. I think that's helpful for someone who's used to looking at HTML source. A step further might be to add a column to the tables with the character reference listed explicitly.
Just a few suggestion. Any thoughts? --Cplot 17:41, 5 July 2006 (UTC)
A couple more comments.To the note, I added the angle brackets from the CJK punctuation category. These look very similar in glyph form and from the name I gather are meant to dennote the nearly same thing in character form. Also I wonder if the note I wrote and the one on unicode support already in the article should not be revised and moved to the top to warn readers of these unavoidable issues? --Cplot 17:50, 5 July 2006 (UTC)

## (Belongs to) ∈ Looks ugly on the main page

It looks kind of weird on the article, but its fine in the discussion page. It does have something to do with the font It looks nothing like the TEX equivalent. [[1]] — Preceding unsigned comment added by 180.215.170.131 (talk) 12:54, 12 January 2012 (UTC)

## Phi

Does anyone know if the ISO standard uses an open phi (${\displaystyle \varphi }$) or closed phi (${\displaystyle \phi }$) for cylindrical and spherical coordinates? Also, is the answer the same for ISO 80000-2? JonH (talk) 07:00, 25 October 2012 (UTC)

The symbol used by ISO 80000-2 (p25) looks to me like the open version, ${\displaystyle \varphi }$. The same symbol is used for both spherical and cylindrical co-ordinates. Dondervogel 2 (talk) 17:16, 25 July 2013 (UTC)
Thanks for the reply. So it seems that Wikipedia is using the correct symbol in this case. JonH (talk) 18:08, 25 July 2013 (UTC)
The correct symbol indeed for phi, but not for theta (also open according to 80000-2). What bothers me is more is the insistence throughout Wikipedia on italicising the mathematical constants e, π and i, which according to ISO should be upright. Dondervogel 2 (talk) 19:05, 25 July 2013 (UTC)

## Inappropriate italicisation

I agree with slawekb. This particular standard might be superseded, but in modern standards, mathematical constants like e, pi and i are upright. Dondervogel 2 (talk) 09:40, 9 May 2015 (UTC)

Yes, in the ISO 80000-2 that supersedes this one, mathematical constants are upright as well. Sławomir Biały (talk) 12:22, 9 May 2015 (UTC)
It doens't matter what the recomendation is... Wikipedia follows standard practice, which is to universally ignore this recomendation. -- [[User:Edokter]] {{talk}} 14:18, 9 May 2015 (UTC)
Yes, in practice thus recommendation is seldom applied. But it is what it is, and this is an article about the standard, which includes typesetting conventions, not standard practice on Wikipedia. If you would like to add a comment to the article that ISO 31-11 is universally ignored in this point (appropriately sourced) then go ahead. But we don't get to make up our own version of the ISO standard just because it disagrees with conventions on Wikipedia. That just makes no sense at all. Sławomir Biały (talk) 16:14, 9 May 2015 (UTC)