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This is a crosspost from the Mathematics Stack Exchange (original post there deleted), I thought I'd ask here as well in case anyone knows. In the STIX package there is a character called \rangledownzigzagarrow, which corresponds to U+237C ⍼ RIGHT ANGLE WITH DOWNWARDS ZIGZAG ARROW in the Miscellaneous Technical Unicode block. What is it meant to represent? Are there examples of its usage?

According to the STIX project, the character is copied from ISO/IEC TR 9573-13:1991, which in turn obtained the glyph from the Association for Font Information Interchange's registry for glyphs in accordance with ISO/IEC 10036. (I've written up the trail here for the curious.) Going by this email from Asmus Freytag, it sounds like anyone could have registered a glyph with AFII for a fee, so the trail kind of goes cold there.

Sir Cornflakes
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ionchy
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    Very interesting email from Asmus. Had never seen it before. Indeed, AFII never did accomplish its intended purpose. – barbara beeton Apr 13 '22 at 02:52
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    https://m.xkcd.com/2606/ – TheAsh Apr 13 '22 at 22:23
  • http://www.jimlynchcodes.com/blog/funniest-unicode-symbol-237c – TheAsh Apr 13 '22 at 22:26
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    It seems that sometimes people have fun inserting funny things in official "places". When I was a university student, a roommate of mine put something like this in the bibliography of his MSc thesis (in chemistry): Simpson, H. J., Burns, M.; The Springfield Journal of Chemistry; "". I won't rule out this explanation for that glyph! :-) – LorenzoDonati4Ukraine-OnStrike Apr 13 '22 at 23:31
  • Awesome question, don't give up just yet, the community might surprise you. – TWiStErRob Apr 14 '22 at 07:28
  • It might be used in the bottom left of a graph where the values shown on the y-axis do not reach 0, as a reminder that the y values shown are not proportional to the heights above the visible x-axis – Henry Apr 15 '22 at 12:59
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    https://www.youtube.com/watch?v=cCoed5Oo_J4 – Azor Ahai -him- May 06 '22 at 22:45

2 Answers2

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This symbol was "adopted" from the existing ISO 9573 standard which defined entities for use with SGML. It appeared in the entity set ISOAMSA, which, regardless of the name, had no connection with the American Mathematical Society; instead, it means "added math symbols", as evident in this listing. I had no idea what the symbol meant or was used for, thus assigned it a "descriptive name" when collating the symbols for the STIX project. (I still have no idea, nor can supply an example of the symbol in use.)

A rather unwieldy position-specific table containing information on the collection submitted for consideration by Unicode can be found via links on the web page https://www.ams.org/STIX ; this is not the final table, which was updated after Unicode assignments were made, but I was pulled from the project before I could complete the tidying up. I am now retired from AMS, and no longer have access to the paper records used to compile the collection; those were left with the intention that they be properly archived, but I have no knowledge of what may have happened to them since.

Paying more attention to the information provided in the question, it is the case that ISO 9573-13 existed long before either AFII or the STIX project were formed. 9573 was an adjunct to the SGML standard, compiled by the same or associated people. I once asked Charles Goldfarb what the source of these entities was, but remember that he didn't have a definitive answer.

Addendum
Even though this question is now closed, there's more useful information available. The OP has done some heroic archaeology, and found among archives holding Monotype punches the actual punch used for producing type for this symbol. A photo of the punch is included in this blog entry. It may have been a special order. The shape differs from the one currently shown in the Unicode charts (I'm going to try to get that fixed), but it's indubitably the same symbol. And we know by this that it appeared in print at one time. But the meaning is still not known.

barbara beeton
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    Ah, so it was added to AFII because it was in 9573-13, and not that 9573-13 simply included all of the AFII entries? I didn't find the character in ISO 8879 on SGML, so it seems like it was added to SGML some time in between the two... – ionchy Apr 13 '22 at 01:32
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    @ionchy -- 8879 provided an "environment", but the entities were defined separately. Although I did ask, no one was able to tell me whether there was a single source or the entities were just picked up from a number of sources. And the inclusion of "AMS" in the names of the entity collections likewise remained mysterious. – barbara beeton Apr 13 '22 at 02:12
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    Many sources think that "AMS" stands for "added math symbols". This character is from "isoamsa" arrow relations. There is also "isoamso" ordinary, "isoamsc" delimiters, and "isoamsr" relations among many others: https://www.mit.edu/afs.new/sipb/project/sgml/share/sgml/catalog – A. Rex Apr 13 '22 at 14:17
  • @A.Rex -- Thanks very much! I've added this information to the answer. – barbara beeton Apr 13 '22 at 15:23
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    Wow. A post from Barbara Beeton with actual, real, capital letters. Do I remember correctly that this means that this is an official stance of the AMS? – mbork Apr 13 '22 at 16:03
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    @mbork -- The all-lowercase mode was significant while I was still employed, to differentiate between "personal" and "official" communications. I retired from the AMS in February 2019, so the distinction no longer matters; all responses are now all my own. – barbara beeton Apr 13 '22 at 16:23
  • Ah, I see. Still, it was a bit of a shock for me. ;-) – mbork Apr 13 '22 at 17:06
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    This answer to the original question on Maths SE sheds some more light, saying it represents a Y-axis continuing below the X-axis, and was used in Dutch economy textbooks. – PJTraill Apr 13 '22 at 19:28
  • @PJTraill As clarified in the comments, it's likely something else this answer is referring to, namely discontinuous axes. – ljrk Apr 14 '22 at 07:56
  • @ljrk: You had me confused, but I see you mean the comments on the answer I referred to. We need to hear if anyone can find this in such textbooks. – PJTraill Apr 14 '22 at 08:36
  • @PJTraill That question/answer seems to be deleted now as it shows 'Page not found'. – Apoorv Potnis Sep 12 '22 at 19:44
  • @ApoorvPotnis That is a shame, especially as I see that this question is also closed as off-topic for LaTeX. I wonder if we have a Stack Exchange site where it would be on-topic. – PJTraill Sep 14 '22 at 00:07
  • @PJTraill It might be on-topic on History of Science and Mathematics. – Apoorv Potnis Sep 14 '22 at 09:40
  • @barbarabeeton I just saw that Anders Berglund was the editor of ISO/IEC TR 9573-13. Do you know if he's still around and might know some of the origins of these glyphs? I've found him at http://www.albconsults.com/, but the site was last updated in 2009. – ionchy Sep 29 '22 at 15:27
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    @ionchy -- I may be able to come up with a contact, I'm trying. – barbara beeton Sep 29 '22 at 19:10
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There was just a YT video about it: https://youtu.be/cCoed5Oo_J4

daleif
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    (this is a bit link-only I guess...) – user202729 May 06 '22 at 23:48
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    The information in the video is inaccurate. It fails to recognize that the inclusion of the character in the STIX collection was based on its presence in a version of ISO 9573-13 earlier than the 1991 version cited, a version which existed long before AFII was formed. So any claim that it originated with AFII is chronologically invalid. – barbara beeton May 07 '22 at 18:21