On 19 Aug 2011, at 15:24, Shriramana Sharma wrote: > On 08/19/2011 07:13 PM, Michael Everson wrote: >> This is a very good question. > > It seems Michael speaks tongue-in-cheek.
Not at all. I think there should be a RTL PUA. > I personally don't see the point in allocation RTL areas in the PUA. It is > after all the *P*UA. Do you expect rendering engines to support the PUA? I can get certain CSUR scripts to behave as expected using PUA code positions. Unless they are RTL. > Yeah OK maybe simply base+diacritic stuff or even ligatures would be easy to > do via simple substitution rules in tables, but how about glyph reordering? No problem unless you are using Uniscribe. > Indic scripts involving reordering and split-positioning vowel signs can't be > handled by placing them in the PUA. There are other ways of handling such clusters. > In what way are RTL scripts different that proper rendering should be > supported for them even though they are in the PUA? They, um, go RTL. > If you want proper rendering in terms of bidi formatting and glyph reordering > etc you should make a proposal for official encoding. The PUA will not help. It would help for exchange of private scripts that are RTL, or for software development of RTL scripts, etc. > Ergo there is no scope for specifying directionality for PUA code-points. Sure there is. It's just giving some otherwise-undefined code points a strong 'R' directionality for the benefit of those users who need to use that. After all, the rest of the PUA gives some otherwise-undefined code points a strong 'L' directionality. Michael Everson * http://www.evertype.com/
