[XeTeX] Arabic Transliteration

[Mohammad Gharaibeh]

Hello all,

I'll create a halfring (left and right) to transliterate a 
arabic hamza and ain. I found it much more confortable, as 
creating an arabxetex environment with the transliteration 
option, because I will transliterate only a few words like 
names.
I just found the other diacritics like \={a} or \d{t} for 
example, but the ain and the hamza I coudln't find.

who can help me?

Regards,

Mohammad