[MPEG-OTSPEC] Feature name parameters in multi-script and multi-language fonts

[John Hudson]

Thanks, Behdad. Peter also explained this in the MS typography issue.

Will investigate possible tooling limitations.

JH



On 2023-10-16 12:00 pm, Behdad Esfahbod wrote:
> Hi John,
>
> What you want is fully doable already. I wrote about it in the older 
> OpenType list one.
>
> The point is that the different language systems can point to 
> different Feature table for the same tag. And it's the Feature table 
> that carries the extra metadata (name-table entry etc).
>
> Hope that helps,
>
> behdad
> behdad
> http://behdad.org/
>
>
> On Sun, Oct 15, 2023 at 10:07 AM John Hudson <john at tiro.ca> wrote:
>
>     I posted this query on the MS typography-issues board back in
>     March, but
>     received no replies.
>     https://github.com/MicrosoftDocs/typography-issues/issues/1015
>
>     My understanding from reading the specification for GSUB feature
>     parameters for Stylistic Sets and Character Variant features is
>     that a
>     single feature parameter can be applied to a feature tag,
>     regardless of
>     how that tag is used in terms of lookup contents for different
>     script or
>     language system tags. Is that understanding correct?
>
>     This seems to me to be contrary to the overall OTL model of script
>     and
>     langsys structures that are specifically designed to enable different
>     writing systems to have different layout behaviours. So, for example,
>     when making a font supporting Latin, Cyrillic and Greek script, it is
>     perfectly feasible for a stylistic set feature such as ss01 to have
>     entirely different behaviour appropriate to each script, and given
>     the
>     limited number of 20 registered stylistic set features this is a more
>     efficient use of the features; also, it is more intuitive for the
>     user
>     of a particular script for accessible stylistic sets in the UI to
>     begin
>     as ss01, ss02, etc. rather than these be reserved to some other,
>     unused
>     writing system.
>
>     There are also cases where behaviour of stylistic set features might
>     differ within a script, at the langsys level. I am currently
>     looking at
>     implementing a stylistic set within the Latin script that is
>     specific to
>     traditional Irish orthography (langsys IRT). Since it is the only
>     stylistic set that would be meaningful within that langsys, my
>     inclination would be to use ss01, but that feature has different
>     behaviour for other Latin script languages, and different behaviour
>     again for other scripts.
>
>     Can anyone see a route out of this, in terms of being able to link
>     feature parameters to specific script/langsys combinations?
>
>     JH
>
>
>     -- 
>
>     John Hudson
>     Tiro Typeworks Ltd www.tiro.com <http://www.tiro.com>
>
>     Tiro Typeworks is physically located on islands
>     in the Salish Sea, on the traditional territory
>     of the Snuneymuxw and Penelakut First Nations.
>
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-- 

John Hudson
Tiro Typeworks Ltdwww.tiro.com

Tiro Typeworks is physically located on islands
in the Salish Sea, on the traditional territory
of the Snuneymuxw and Penelakut First Nations.

__________

EMAIL HOUR
In the interests of productivity, I am only dealing
with email towards the end of the day, typically
between 4PM and 5PM. If you need to contact me more
urgently, please use other means.
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