Danny responded, but it sounds to me like the Validator was being asked to process an error message.  

del.icio.us RDF to OPML Reading List 

I just came across a good post by Danny Ayers in which he describes a nice way to use XSL to transform an RDF feed from del.icio.us into OPML.

However, he complained that he could only get his OPML to validate by omitting the XML declaration.

That sounded wrong, and sure enough, it was.

I grabbed his XSL and his RDF feed, and changed the XSL to permit the XML declaration.

Here's the result.

As you can see, it's valid, and it validates.

Yet he deleted my two comments in which I pointed this out and asked him what error message he got. It would have been nice to know what the error message was to let someone try to reproduce the error and/or correct any bug in the validator. What the heck? Now the comments are back. I'm guessing he didn't actually delete them, but that there was some sort of caching weirdness (even though I had seen them before they disappeared), or maybe because I posted two consecutive comments they got flagged as spam. So, I hope he responds so that the error he saw can be checked out, etc.