[XeTeX] On combining diacritics again

[Nicola Vitacolonna]

> It's true, to some extent, that it depends on the text rendering
> engine, in the sense that the Cocoa TextView (as used in TextEdit,
> TeXShop's editor window, etc) will stack diacritics automatically,
> without any specific help from the font. The positioning of the
> diacritics may not be ideal, however; it's often more widely spaced
> than a type designer would prefer.
>
> XeTeX doesn't do this; it *only* performs diacritic positioning (etc)
> in accordance with font tables. Gentium doesn't currently include
> OpenType tables, and so diacritics won't stack; Charis SIL and Doulos
> SIL do have OpenType positioning tables, and so diacritics will stack
> properly.
>
> JK

Thanks, your answers are very clear. But my question was a bit  
different, and I'll try to be more precise: is there any difference  
between U+0117 (Latin Small Letter e with Dot Above) and the pair U 
+0065 (Latin Small Letter e) plus U+307 (Combining Dot Above)?  
Stacking a diacritic over the former is handled in the same way as  
stacking a (second) diacritic over the latter? Does it depend on the  
font?

Nicola