Automatically discovering available extensions

I'm testing a product that supports XSLT by embedding some version of
Xalan. (Not the Java version.) There is no documentation available on
what extensions are available in this version of Xalan. Is there any
way to write a stylesheet that discovers the available extensions? 
Such as (in pseudocode):

   Loop (through extensions)
         print etension name
    End loop

I guess I could test specific extensions with fallbacks, but that's
not exactly the same thing.

Thanks,

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 David Adams
  dpadams(_at_)gmail(_dot_)com
 Bermagui 2546 NSW
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