[XeTeX] openType and xetex

[Youcef Mohammed]

when i used the KFGQPCUthmanicScriptHAFS font -wich is an openType
font dedicated to the holy Quran- in a document containing Quran text
(from the KFGQPC) and compile with xelatex i find that Marks are not
correctly  positionned or not positionned at all; especially whene
there is more than two successive marks... so who can tell me what
openType features are not yet implemented in xetex...
thanks.