Add characters to support Turkish to Serif Initials

[alerque]

The Serif Initials currently has very limited language support due to a limited character set. At least for my own modern use I'd like to expand this to at least cover the few missing characters needed for proper Turkish support.

• Â
• Ğ
• Ş
• İ

Of these the first two rarely show up at the start of a word, so initials wouldn't get much use, but for completeness I think they should be covered.

Also even more rare but that do turn up in historical stuff:

• Û
• Î

(SILE code)

```sile \begin{document} \font[size=40pt] \font[family=Libertinus Serif Display]{Â Û Ü Ö Ğ Ç Ş İ Î} \font[family=Libertinus Serif Initials]{Â Û Ü Ö Ğ Ç Ş İ Î} \end{document} ```

[Crissov]

Shouldn’t Ç and Ş (optionally) use a dot below instead of a proper cedilla in Turkish locl?

[alerque]

I've never heard of using a dot-below instead of cedilla in Turkish (and I live in Turkey and publish books in Turkish). A comma-below got used as a lot as a poor man's substitute back in the typewriter days and still lives on in the computer age where stupid internet tools allow people to copy/paste things like c+combiner+, to allegedly "add Turkish support to fonts that don't have it". Also the Swiss modernist style of cedilla that is disconnected and looks more like a comma comes in and out of fashion occasionally. But as far as I know the official alphabet and orthography has always called for a proper cedilla. I'd be fascinated to read about it if you had a source for something else though.

[Crissov]

I'm seeing the dot below quite regularly on well-made signs of Turkish shops here in Germany, although not in the majority of cases by far. I once read the custom came from the influence of Arabic typography, because the dot (or diamond) is the standard "diacritic" there. My impression is it is more common for sans-serif fonts, so perhaps not really appropriate here indeed.

[alerque]

Now you've piqued my curiosity! If you think of it next time you bumped into ones that are clearly not just dump hacks but the result of actual design can you snap me a picture? I'll be curious to see what fonts out there are doing this. Even if it turns out to be a localized design trend influenced it would be interesting to know about — and if not for Libertinus Serif Initials, maybe a stylistic alternate set for Libertinus Sans would actually make sense!

(If you do come up with something lets break out a new issue to track this since the resolution will be different than what will eventually close this issue.)

[Crissov]

If you look at merch for Beşiktaş Istanbul, for instance, you should easily find examples. That being said, you will also find a variety of other cedilla designs.