debian: FOP and %isotech in PDF output

Hi there,

  I am trying to understand how to configure fop to properly generate
proper PDF file when input XML contains unicode from -say- %isotech.
Is there a way to tell fop to fail when output will be incorrect
(fonts does not contains a particular symbols) ?
Is there a fonts I should be using on my debian/linux system that
contains everything (I need at least %isotech).


Thanks a bunch !
-- 
Mathieu