Timo,
The w3c validation page is a bit confusing in regards to this. When name is used, there are no warnings or errors. But when id is used, the error message states that both name and id cannot start with a number or it is not a valid naming. Maybe I am reading the error message wrong, but the way it's phrased there it sounds like both methods should throw an error in regards to validation when they start with a number. Perhaps the message wasn't updated when they deprecated the name method of naming... it makes their rules seem contradictory to each other to state in one place you can't start with a number as a name with "name" or "id", but then validate it when "name" does start with a number without even a warning.
I still feel that while validation is becoming more and more important, it's really more important for the browsers themselves to work on compliance so they all render the same html in the same way before we place too much importance on compliance. Unfortunately, many end users don't see it that way and some, as government orgs, don't have a choice in the matter. Still, I think there should be more pressure on the makers/creators of the browsers out there to step up along with the web designers.
But, I digress. I had to install a separate install of dnn5.0.0 to verify it was doing something different from dnn5.00.01. Also, I looked through the code to find where this tag was being injected from and couldn't find it, I'm assuming it must be something compiled in one of the dll's. So, I'll just wait for the next release and feel better about not having modified the core code at all.
Thanks for taking care of this.