Hello, I use Google Fonts as a reference to learn from. They all create a default (DFLT).
Do I really need to create one?
Or do I just need Arabic (arab)?
Quick answer — include both scripts
arab– holds all Arabic-specific shaping lookups (init,medi,fina,rlig, etc.).DFLT– a safety-net script that shaping engines fall back to whenever they don’t detect a specific script (for example, a run consisting only of digits, punctuation, or symbols). Putting your generic lookups here ensures things like kerning, ligatures, and mark positioning always work.
Why it matters:
If a text run contains only figures, the shaper will not label it as arab, so any digit-kerning stored only in arab would be ignored. Duplicating the same kern lookup in DFLT prevents that problem.
Although DFLT isn’t mandatory in the OpenType spec, it costs only a few bytes and protects you in older apps and odd edge-cases. That’s why Google Fonts—and most foundries—always add it, even to fonts that otherwise contain only Arabic glyphs.
Thank you very much and sorry for bothering you with my questions.
I know these questions are not related to the program but rather to user knowledge.
So, thanks and appreciation are due.
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