🥢 ionchy 🏳️‍🌈

yeah that was me, I wrote about U+237C right angle with downward zigzag arrow/⍼. I have a new blog post about some relevant Monotype documents I looked at while visiting St Bride Library in London:

for those of you who don't know, back in 2022 I started investigating some unexplained glyphs encoded in Unicode's Miscellaneous Technical block. there's actually quite a lot of unexplained or incompletely-explained glyphs from back when the Unicode standard was newly borne out of a slew of other character encoding standards. U+2107 ℇ Euler's constant, for instance, was copied from a Xerox standard, but clearly isn't the glyph we use for anything we call Euler's constant. I actually started out looking at the range U+23BE..U+23CC, which turned out to be Japanese dentistry symbols, and not merely Palmer notation.

Unicode is fairly inconsistent in naming its codepoints because sometimes they're semantic and sometimes they're syntactic glyphic (?). for instance, in that Miscellaneous Technical block, the name of U+23E7 ⏧ electrical intersection describes what the glyph is meant to represent, rather than a description of the glyph (which would make it, I dunno, "node with incoming edges"?). one of the dentistry symbols I mentioned, U+23C5 ⏅ dentistry symbol light up and horizontal with triangle, describes the visual depiction rather than what it represents: bottom artificial teeth.

the glyph I decided to investigate was U+237C ⍼ right angle with downward zigzag arrow, squashed between a section of APL symbols and some control code pictures. the journey to tracking it down as far as I have is a long one, but the path¹ is actually quite short:

• the Unicode proposal that included ⍼ took characters from
• the STIX fonts project by the AMS, whose character compilation was led by Barbara Beeton, who took characters from
• a technical report for SGML on character entities², edited by Anders Berglund, who took characters from
• Monotype's List of Mathematical Characters from 1972, with a list of the characters in their L231 series, which includes ⍼ under matrix number S16139, printed using
• a physical punch³, formerly part of the Type Archive's collections, now held by the Science Museum Group

here's three images from the end of this journey that I think are the most interesting. the first two below are scans from the List of Mathematical Characters, and third is a photograph of the box of punches. it's wild to think about how this funny symbol ⍼ started out as a physical bit of metal sometime prior to 1972.

L231 page w/ ⍼ on second column, third from bottom First page of the List Box of L231 punches w/ ⍼ on seventh row, third from right

two weeks ago, I had the opportunity to physically take a look at the List myself at St Bride Library in London, along with various other Monotype documents on mathematical and other special characters. although I technically had the opportunity since last year to see more of the List by requesting scans from the University of Cambridge library, who also own a copy, it was really cool being able to flip through it myself. one part I want to point out is this excerpt from the second image above (emphasis mine):

It should be understood that Series 569 contains only those characters which are (a) mathematical and (b) recognised internationally. We are periodically asked to supply characters which do not meet these conditions. In order to meet such requests we have therefore provided the supplementary fount L231.
L213-10 pt has the same Group numbers, and conforms with Series 569 in all respect of matrix manufacture, casting and usage. However, we do suggest that customers, on finding that a particular character they require is made in L231, should, nevertheless, still endeavour to persuade their customer or author to use normal notation from Series 569. We shall be only too pleased to provide any relevant data regarding why the character has been made in the L231 category, should this be requested.

if only the typesetting branch of Monotype Corp. Ltd. still existed in any sort of meaningful way! because ultimately, there are still a lot of questions about ⍼ to be answered:

• who commissioned this character?
• in what publications was it printed?
• what does it mean??

1. if you're looking for proper references, check out those three blog posts I wrote

2. this is also where the HTML entity reference ⍼ comes from

3. more precisely, the punch was used to strike a matrix, which was then used to cast type, which was then used for printing