[Fontconfig] Asking FontConfig for a font that supports a script

[Sairus Patel]

I want to query FontConfig:
- "give me a font for Latin characters"
- "give me a font for Simplified Chinese characters"
- "give me a font for Mathematical symbols"
etc

Do I use FC_LANG when creating the pattern? It doesn't seem quite the right fit, since there are several languages, including "en", that use Latin characters. Yet the codebase I'm dealing with uses FC_LANG for this.

I thought FC_CHARSET might be a possibilty, but I don't see it used in FcDefaultSubstitute.

If FC_LANG is what I should use, then is the valid list of parameter values ISO 639-1? This seems to be suggested by http://www.freedesktop.org/software/fontconfig/fontconfig-devel/x31.html#AEN44.

Or is it up to the person who sets up the config files?

I looked at thread "ISO 15924 font selection" in the archives but didn't see any resolution.

Thanks,
Sairus