RE: Is it an error if can't resolve uri-reference?

> Is it an error if, when processing an include or import element, a 
> stylesheet processor can't resolve the href uri-reference?

Yes, it's an error.
> 
> The 1.0 spec doesn't say that it is. Or did I miss it?

The 1.0 spec doesn't try to list all the things that can go wrong.
> 
> I see that Xalan reports it as an error. Saxon 7.8 probably does too, 
> though what I see is it doesn't catch the FileNotFound exception.
> 

I'm not sure what you mean by this. Apart from anything else, that's not the
exception you get when a URI can't be resolved.

Michael Kay