Open Font Format Layout Tag Registry

Does this registry exist?  If so, how do I access it?  The nearest I can find is Microsoft's OpenType Layout Tag Registry, which is declared to contain the tags recognised by Microsoft.  I am specifically looking for script tags such as dev3 and ory3.


  • John Hudson
    John Hudson Posts: 3,017
    edited July 2022
    The dev3 and ory3 etc tags are non-standard. When Microsoft published the Universal Shaping Engine specification, there was some talk about defining new tags for scripts processed by existing Indic shaping engines that would direct layout processing via USE instead. Apple made and shipped an experimental implementation of the xxx3 tags for such scipts, so it is possible to use those scripts in fonts and have CoreText pass them to its USE implementation. But these tags have never been properly documented, and they are not standard to either OpenType or the Open Font Format. The closest I can recall seeing to documentation was a list of the Indic properties mappings that Apple used for characters in those scripts within USE. Sorry, I can’t remember where that was or if it was public.

    [I believe, at present, the OFF tag registry is identical to the OT one.]
  • Simon Cozens
    Simon Cozens Posts: 726
    I was thinking the other day how useful it would be for the OT tag registry to be an actual machine-readable database - perhaps something similar to the IANA language tag registry - not just an HTML table. Shaping engines, font compilers and toolkits all rely on this stuff, and we have to scrape it off a rendered page and hope that the format never changes.