[MPEG-OTSPEC] VARC issues with the published OFF 5th ed

[Behdad Esfahbod]

Thanks Vlad,

What would be the deadline to submit contribution for the October 19-24
meeting?

I'm hoping that we can get away with a corrigendum.

behdad
http://behdad.org/


On Sat, Oct 3, 2026 at 10:54 AM Vladimir Levantovsky <
vladimir.levantovsky at gmail.com> wrote:

> Hi Behdad, all,
>
> To start the process of making corrections, it would be ideal if you
> prepare an input contribution for the upcoming SC29/WG3 meeting that will
> be held on October 19-24.
>
> Depending on the amount and the severity of proposed changes, we can
> decide whether issuing a corrigendum would be a suitable option, or if it
> requires an amendment. A corrigendum would be quicker path forward; an
> amendment would have to follow the typical path of WD - CD/PDAM - FDAM
> (with ballots issued at every stage), before it is finalized and published.
>
> Thank you,
> Vladimir
>
> On Oct 2, 2026, at 9:18 PM, Dave Crossland <dcrossland at google.com> wrote:
>
> 
> Thanks for flagging these, Behdad. Glad to see you're cross-checking the
> implementations already.
>
> Vlad, sounds like this is enough to Kickoff a 1st amendment :) if so, what
> would you for cast as an overall end to end timeline?
>
>
> --
> [image: GDP logo]
>
>
> Dave Crossland
>
> Font Expert
>
> Google Design Platform
>
>
>
> On Fri, Oct 2, 2026, 3:30 PM Behdad Esfahbod <behdad at behdad.org> wrote:
>
>> Hello everyone,
>>
>> Thank you, Vlad, and everyone else who worked in the past four years to
>> get the boring-expansion proposals into the ISO OFF 5th ed.
>>
>> Since the PDF became freely available on Monday, I've been busy
>> cross-checking my implementations against the spec. Generally things are
>> holding up well, but unfortunately I discovered three issues in the VARC
>> table that I recommend fixing in the spec. Details and recommendation in
>> the github issues:
>>
>>
>> *1. VARC ConditionList: restore omitted uint32 conditionCount*
>> This one is was lost in translation from my working design to the ISO
>> proposal. It's currently impossible to implement the ISO spec, because it
>> defines an array without defining its length anywhere:
>>
>>   https://github.com/harfbuzz/boring-expansion-spec/issues/176
>>
>> *2. VARC: make SparseVariationRegion axis offsets table-relative and
>> correct its designation*
>>
>> This was was a mistake from the review modifications of the table format
>> to promote a struct to a table, but this was not done properly. Offsets
>> should be relative to the beginning of their table, not the grandparent
>> table as currently speced.
>>
>>   https://github.com/harfbuzz/boring-expansion-spec/issues/177
>>
>> *3. VARC: Remove the exception to ordinary LSB/origin alignment for
>> components*
>>
>> This is a design leftover from when I had encoded the variable-composites
>> in the `glyf` table. In that design, the recommendation made sense. In a
>> separate `VARC` table, it doesn't, and hinders implementation. This change
>> wouldn't affect properly-made fonts (lsb=xMin).
>>
>>   https://github.com/harfbuzz/boring-expansion-spec/issues/173
>>
>>
>> That's it for now. I will be spending a lot more time with the spec, but
>> I don't expect other major issues to arise.
>>
>> Thanks,
>> behdad
>> http://behdad.org/
>>
>
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