My assumption is that you are using .NET and this is custom
URIResolver
that you are referring to?
.NET chose to call its version of the URIResolver an XmlResolver, so I
suspect the question relates to Java JAXP rather than .NET.
Either way, it doesn't matter because the
easiest way to solve your problem is to wrap the document() function
within a boolean() function which will evaluate to true if the file
exists and false if it does not.
That only works if the XSLT processor chooses to take the (optional)
recovery action from the error that occurs when a document can't be found.
So this solution isn't portable.
Michael Kay