[MPEG-OTSPEC] checksums in TTCs

[Ken Lunde]

Peter,

While this does not answer your request, as far as I am aware, the two publicly-available tools that compile multiple OTFs or TTFs into a TTC are otf2otc (AFDKO) and ftxmakettc (Apple Font Tool Suite). There are probably more. There is also support in fontTools for TTCs.

I am aware that otf2otc makes tweaks to some tables, such as the 'name' table, while it is assembling the tables into a TTC. Also, both tools accept TTCs as input, which is useful for merging multiple TTCs into a larger TTC that includes more fonts.

Regards...

-- Ken

> On Sep 4, 2020, at 13:25, Peter Constable <pgcon6 at msn.com> wrote:
> 
> The OT spec and OFF currently don’t really make clear, when generating a collection file, how table checksums (for tables that get changed during the merge) or head.checksumAdjustment should be handled. I’ve some thoughts on what might or might not make sense. But I’m curious to know what is currently being done in any tools that generate TTCs / OTCs.
>  
> I’d welcome input either here or in the discussion for this OT spec issue:
>  
> https://github.com/MicrosoftDocs/typography-issues/issues/417
>  
>  
>  
> Thanks
> Peter
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