u+0035 – u+0038

James Puckett

Are the following unicode points used for anything? It seems like they would have been combined with other letters to create ŧ, ł, ø, etc. in a font that doesn’t support these glyphs. Would adding them to a font today serve a purpose?
u+0035 Short Stroke
u+0036 Long Stroke
u+0037 Short Slash
u+0038 Long Slash

And the same for U+0312, Combining turned comma above. Is that just for creating ģ?

John Hudson

Re. the first four, probably not. Unicode's practice in recent years is that diacritic letters involving overlaid slashes or bars should be independently encoded without canonical decompositions. This is in recognition that it is seldom adequate to display such letters using combining overlay marks. These marks precede that decision, and some diacritic letters may have canonical decompositions that reference them — I can't recall off-hand, with certainty —, but typical layout engines would perform cmap substitutions of decomposed strings to the precomposed diacritic characters, so even in this instance there's probably no need to include these marks in the font.

Re. U+0312. It's useful, as you note, for creating the ģ as a composite, and since the shape exists, it might as well be encoded and put in an appropriate mark position class. There's always the chance that some orthography, somewhere in the world, today or tomorrow, will use it as a distinct diacritic mark.

Igor Freiberger

Solidus (0338) is used in several Mathematical operators or signs, like ∅, ⊄, ∉, ⊉ or ≇. Unicode refers to it as a component for all those.

The others —0335, 0336, and 0337— aren't present in Unicode as components. But what John said about 0312 also applies to them. All are useful for creating composites like Ł, Ƀ, ѣ, ꙃ, ᴃ or Ꝅ.

If you plan a really deep language support, there are some non-encoded characters which also use these diacritics, as barred Iota or L with double stroke.

Maybe the first three have additional importance for non-coded phonetic composites. They are present in Stone Serif Phonetic and SIL fonts.

James Puckett

Thanks!

John Hudson

Igor, I find that overlay composites seldom work, as the presence of the stroke requires adjustment to the underlying letter, and typically the length and sometimes angle of a slash or bar needs to be adjusted too.

Igor Freiberger

Agreed. I was stressing the purpose of the diacritics James asked about, but even for precomposed glyphs some (or several) variants are needed. My set:

Khaled Hosny

U+0338 is used in math quite often with any arbitrary math symbol. The TeX equivalent of, say ⊄, is encoded as two characters and requires two TeX commands to produce it (\not\subset), and TeX users come to expect they can negate any symbol, so some TeX engines supporting Unicode and OpenType has special “math accent” for overlays that centers them vertically and horizontally relative to their bases.