URL encoding

[Dave Blake]

I'm constructing a URL in XSL to use as a reference to an external XML 
fragment in document() call. I need to encode the parameters used in the 
URL (space to %20 for example). These parameters are pulled in from an 
XML file which are not URL encoded. I was wondering what the generally 
used solution to this problem is when using Xalan (XSLTC engine). From 
what I can tell, Xalan doesn't have a built in encodeURL type function.

Any help would be appreciated!
Dave.