[ft] What do kerning values mean in RTL text?

[Paul Pedriana]

I'm trying to understand how kerning is done in RTL text and can't find 
any documentation (on the Internet nor in Freetype) that addresses this.

Questions:
  - Do kerning pairs in RTL refer to two sequential glyphs in logical 
order or visual order?

  - If there is a string with the logical order is CAT and a visual 
order of TAC,
     do kerning adjustment pairings apply for CA (logical order) or for 
AC (visual order)?

  - Given that the RTL layout alrogithm 
(http://freetype.sourceforge.net/freetype2/docs/glyphs/glyphs-5.html)
     specifies that advance width of C (from our CAT above) is applied 
before the positioning
     and drawing of C, how and when and in what way is a kerning 
adjustment applied?

If I can get this answered, I would like to document this and contribute 
the documentation to the Freetype project, as this is something that 
appears to have flummoxed a lot of people. Every description of kerning 
I can find discusses LTR kerning and unfortunately seems to leave RTL 
kerning as an "exercise for the reader".

Thanks.