[MPEG-OTSPEC] CFF2 errata

[Behdad Esfahbod]

Hi Skef,

Thanks for the prompt reply. The two proposals look good to me. One comment
below:

On Fri, Nov 1, 2024 at 3:59 AM Skef Iterum via mpeg-otspec <
mpeg-otspec at lists.aau.at> wrote:

>
>    - The proposal to allow multiple vsindex operators in a CharString is
>    a very significant change that will need further discussion both within
>    Adobe and probably outside of it. It will probably require bumping the CFF2
>    major version number (to 3, alas).
>
> Not the minor version? What things would trigger a minor-version bump?

>
>    - We will need to consider whether to allow the change in the
>    PrivateDict as well, and what that means for fallback (what the first
>    proposal clarifies). All of this means that this is not the time to be
>    discussing that change.
>
> I think multiple vsindex'es are already permitted in PrivateDict. At
least, there's no text saying otherwise. The relevant text in the spec is:

"The vsindex operator may be used only once in a CharString and must
precede the first use of the blend operator."

Thanks,
behdad


>
>
> Perhaps we can discuss the two editorial(esque) changes at our next
> meeting.
>
> Thanks,
> Skef Iterum
> Adobe, Inc.
>
> On 10/22/24 3:17 PM, Behdad Esfahbod via mpeg-otspec wrote:
>
> Hi everyone,
>
> CFF2 has a file size advantage over TrueType-flavored variable fonts,
> specially if one doesn't care about hinting (Android, Apple platforms, etc)
> but does care about (uncompressed) size.
>
> CFF2 also alleviates some other limitations of variable-fonts built
> against the gvar table. Unfortunately, it imposes its own limitations.
> These are among the issues I'm going to raise.
>
> Please see:
>
>   https://github.com/harfbuzz/boring-expansion-spec/issues/155
>
> for details of the changes I am proposing. Ideally, Adobe folks choose to
> turn these ideas into proposals and push it through the OFF standardization
> / OpenType integration process. Failing that, we might want to go ahead and
> do it at Google
>
> Thanks,
>
> behdad
> http://behdad.org/
>
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