[MPEG-OTSPEC] [EXTERNAL] Shared GSUB/GPOS notes, was Re: dmap proposal

[Liam R. E. Quin]

On Wed, 2024-01-03 at 17:58 -0800, John Hudson wrote:
> > 
> >  So it seems like the only reason for needing separate GSUB or GPOS
> > tables would be if the scripts, language systems or features needed
> > to be different. Is that ever necessary?
> 
> Yes, see e.g. Nirmala UI and Nirmala Text, which ship as a single TTC
> with a common glyf table but distinct GSUB and GPOS supporting
> different behaviours for the same glyphs in different target
> environments.

Would it make more sense, instead of a DMAP table, to have a TTC header
field that lists tables that should be treated as delta tables - i.e.
look in this GSUB first and then this other one?

At any rate i'm working on a revised DMAP proposal, as per the last "ad
hoc" call, and plan to make it public this coming week after i finish
working on the other proposal... so then we'll have something concrete
to discuss.

Right now it's the same as the rather brief DMAP section in the main
Google Fonts proposal, except it'll have more text and a pretty picture
to try & give more context. But thats only because its what i have, not
an expression of an opinion.

liam

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Liam Quin, https://www.delightfulcomputing.com/
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