One year ago, on 28 February 2025, Wikipedia user Moyogo updated the page for Angzarr with a citation to the type foundry H. Berthold AG’s 1950 symbol catalogue listing ⍼ as Azimut, Richtungswinkel, or “azimuth”, “direction angle”. Mystery solved!

Fonts in Use lists links to archived catalogues by Berthold. The above scan is from the 1950 Zeichenprobe (symbol catalogue) on page 7. Copies of the Schriftprobe (font catalogue) from 1949, 1951, and 1952 all show on page 104 the same glyph and sizes, albeit without the descriptor name.

⍼ does not appear in the 1946 Registerprobe, nor in earlier 1909 and 1900 catalogues. For convenience, I’ve extracted full-page scans below for where it appears — and where I feel it would appear, but doesn’t.

A friend on Mastodon pointed out that the glyph ⍼ itself resembles the way a light ray passes through a sextant to measure an azimuth, with the right angle being a standard symbol for an angle in general. Wikipedia has a lovely illustration demonstrating how a sextant works to measure latitude of the sun; it can, of course, be turned sideways to measure an azimuth with respect to an arbitrary meridian.