How do I check for the existence of an external file with XSL?

Question

I\'ve found a lot of examples that reference Java and C for this, but how do I, or can I, check for the existence of an external file with XSL.

First, I realize that

Answer 1

EDIT: Use unparsed-text-available function. It is part of xslt 2.0, but not XQuery or standalone XPath.

I've left my previous answer here so you can follow the trail of uncertainty...

I don't believe there is a way of doing this in XSLT using the standard functions. You can do it using extension functions, as described here, for java.

There is the unparsed-text-available function, but I'm unsure if this is a standard function. There's an example of it's usage at Zvon. The unparsed-text-available is mentioned here as being part of xslt 2.0, and is supported in Saxon.