Half brackets from Supplemental Punctuation block. Is there a standard for them?

Stefan Peev

I was asked to add half brackets: uni2E22 (TOP LEFT HALF BRACKET), uni2E23 (TOP RIGHT HALF BRACKET), uni2E24 (BOTTOM LEFT HALF BRACKET), uni2E25 (BOTTOM RIGHT HALF BRACKET) to the project Common Serif. I used 3 control fonts (Brill, DejaVu Serif, Gentium) to find out which is the the appropriate way to embed the half brackets. Is there any standard for half brackets or designer may decide how long to do these glyphs? Thank you in advance for your assistance.

Stefan Peev

Some information about half brackets on Wikipedia:

Quine corners ⌜⌝ and half brackets ⸤ ⸥ or ⸢ ⸣

The Quine corners ⌜ and ⌝ have at least two uses in mathematical logic: either as quasi-quotation, a generalization of quotation marks, or to denote the Gödel number of the enclosed expression.
Half brackets are used in English to mark added text, such as in translations: "Bill saw ⸤her⸥".
In editions of papyrological texts, half brackets, ⸤ and ⸥ or ⸢ and ⸣, enclose text which is lacking in the papyrus due to damage, but can be restored by virtue of another source, such as an ancient quotation of the text transmitted by the papyrus. For example, Callimachus Iambus 1.2 reads: ἐκ τῶν ὅκου βοῦν κολλύ⸤βου π⸥ιπρήσκουσιν. A hole in the papyrus has obliterated βου π, but these letters are supplied by an ancient commentary on the poem. Second intermittent sources can be between ⸢ and ⸣. Quine corners are sometimes used instead of half brackets.

Stefan Peev

Another position from Unicode forum at Reddit:

Are you bothered that the top of the bottom half brackets doesn't line up with the bottom of the top half brackets in two of these typefaces? These aren't meant to be drawing tools.
The specifications for this block of characters (https://unicode.org/charts/PDF/U2E00.pdf) says the following interesting things:
Fonts
The shapes of the reference glyphs used in these code charts are not prescriptive. Considerable variation is to be expected in actual fonts.
Half brackets
These form a set of four corner brackets and are used editorially. They are distinguished from mathematical floor and ceiling characters. Occasionally quine corners are substituted for half brackets.
2E22 ⸢ TOP LEFT HALF BRACKET
→ 2308 ⌈ left ceiling
→ 231C ⌜ top left corner
→ 300C 「 left corner bracket
2E23 ⸣ TOP RIGHT HALF BRACKET
2E24 ⸤ BOTTOM LEFT HALF BRACKET
2E25 ⸥ BOTTOM RIGHT HALF BRACKET
Note the alternate characters for other uses.

Denis Moyogo Jacquerye

The proposal that added the half bracket characters, Everson et al., Proposal to add Medievalist and Iranianist punctuation characters to the UCS, N3193, L2/07-004, 2007, says the following:

The scholarly HALF BRACKETs have been found with some glyph variation, sometimes looking like QUINE CORNERs and sometimes like the FLOORs and CEILINGs; this is probably due to available fonts more than anything else—the “real” character is a half a bracket, or a bracket cut in half.

[...]

The ideally-formed half bracket is half a bracket.