[MPEG-OTSPEC] Possible edit for LTSH and b64k

[Takaaki Fuji 藤 貴亮]

Hello all,

Sorry if I missed past discussions, but I found LTSH might also need a small change for the b64k proposal, where the 'numGlyphs' field is uint16.

I checked the fonts currently available in macOS and Windows, and still a number of fonts include a set of VDMX/hdmx/LTSH table, possibly generated with the Microsoft’s CacheTT tool. I also found out that B612 (https://b612-font.com) is one of the recent fonts with those tables.

For b64k fonts, I suppose just capping this field at 65,535 should suffice as you can put an arbitrary number of 'yPels' in the table anyway. Like the 'sbix' table, putting a line like

> The glyph count is derived from the size of the ‘GLYF’ table when present, or from the 'maxp' table. 

into the description sounds nice to make sure b64k-aware clients should ignore the ’numGlyphs’ field in this table.

So, in case this table is still in use, we might want to make a small edit. What do you think?

Regards,

Takaaki Fuji