Patterns for encoding simple type validation results

I'm looking for a good way to encode simpletype-related errors within an
XML message.  The idea is that a process will do schema (or other)
validation of some XML data, and then generate an XML-format report
listing the simpletype- (or other)- related errors. I'd want the report to
be as specific about the error as possible, for example by indicating
which constraining facet has been violated if this is simple type-related
validation error. 

I can see a few ways of doing this, but just wondered if anyone has
already thought about this ..

Ian