[XeTeX] using different fonts for one language (Syriac)

[Philip Taylor (Webmaster, Ret'd)]

Ulrike Fischer wrote:

> Text with "western script" can easily use different fonts or
> variants: You can change the family (\ttfamily, \sffamily,...) or
> switch to a variant with \itshape. Similar things can naturally be
> done with other scripts too. Check the fontspec documentation for
> ideas.

I'm way out of my depth here, but looking at the entry for Syriac
in Daniels & Bright;s "The World's Writing Systems" is seems to
me that it would be a major deviation from the intended and
apparent meaning  of \ttfamily, \slfamily or \itshape
if one were to try to use them for switching between Estrangelo,
Serto, Nestorian & Jacobite.  Are there no more better hooks
that can be used for switching between related scripts that do
not fall into the categories that Ulrike proposes ?

** Phil.