[MPEG-OTSPEC] Does a rendering system know if a variation selector requested glyph is not available in a font?

[William_J_G Overington]

        ------ Original Message ------
        From: john at tiro.ca
        To: wjgo_10009 at btinternet.com; htl10 at users.sourceforge.net; 
mpeg-otspec at lists.aau.at
        Sent: Friday, June 21st 2024, 00:27
        Subject: Re: [MPEG-OTSPEC] Does a rendering system know if a 
variation selector requested glyph is not available in a font?


       On 2024-06-21 3:41 pm, William_J_G       Overington wrote:
       It       did occur to me that, in my opinion, it would be better 
to encode       256 User-Defined Variation Selectors.     Unless you are 
anticipating 256 variations of a single character       needing to be 
captured in plain text, that would be significant       overkill. 
Indeed, even if the arguments of the proposal document       are 
accepted, I doubt if 128 codepoints would be assigned to 
implementing it. I suspect 64 would be plenty and 48 would probably 
suffice.
       Remember: a) you only need enough variation selectors to address 
the number of variants, not the number of characters of which 
there are variants; and b) these would be the equivalent of PUA 
variation selectors, so with no guaranteed interoperability beyond 
private agreement among font makers and within user communities. 
So the variation selectors would be shared among characters and 
also across fonts for different fields and communities of 
scholars.
       JH

       --

  John Hudson
  Tiro Typeworks Ltd    www.tiro.com

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