Solution for Extended Tamil

[Richard Wordingham]

On Mon, 22 Jan 2024 18:23:03 +0000
James Kass via Unicode <unicode at corp.unicode.org> wrote:

> Has any effort been made to use OpenType to get the desired display?  
> Classifying the superscripts digits as "marks" in the GDEF (glyph 
> definition) table and then using GPOS (glyph positioning) for the 
> desired placement?  Or has the user community accepted the plain-text 
> legibility of the /de facto/ standard encoding order and reconciled
> with the fact that not all published books can be exactly rendered in
> plain-text?

I think the first big question is whether the font (envisioned as active
code) will be presented with letter, non-ligating right matra and digit
in the same glyph run.  If that happens, I would start with them as base
characters in the GDEF and treat it as an exercise in reeordering at
the GSUB level.  It's no worse than the re-ordering I do to render Tai
Tham starting from the characters transcoded to Latin letters, even if
there be a mark between matra and digit. The digits need to be bases -
I can imagine a sequence <KA, AA, SUPERSCRIPT TWO, ZWNJ, SUPERSCRIPT
TWO> where the second SUPERSCRIPT TWO is referencing a footnote. The
other big question is whether the reordering is compliant with Unicode.

Using GPOS for re-ordering seems to be a nightmare.

Where do you get this 'non-reordering' property from?

Richard.