[XeTeX] substitutions for missing or wrong glyphs

[Susan Dittmar]

Hi folks,

I guess this is a FAQ, but my search foo seems to have left me today...

I would like to use a font (several in fact, some of which are true type,
others open type) which does not include all glyphs I need.  For example
the endash and emdash are missing, as are the german quotation marks. Is
there a way, other than hacking the font file itself, to tell xetex to take
those glyphs from another font? I know that might look ugly, but it's still
less ugly than the 'missing glyph' glyph or another completely wrong glyph.

Thanks for any hints,

	Susan