because i want to use math, chemical signs, functions, very elegant
transfoms etc
but everytime i want to use them i have to make a copy of the file and
put in the same directory i am saving my xml. you can tell me how to
install them so that i don't even need to copy any of them but still am
able use them directly.

I am thankfull for any help. please..

Sounds like you've provided a relative URI to the XSL. Switch to an
absolute URI, or at least one which is rooted.

--
Joe Kesselman / Beware the fury of a patient man. -- John Dryden