Am I losing it?

I'm in dire need of some help here, so any info is seriously appreciated.

1. I cannot find any more information on the current dtd, or any other pretainent info about XML. It used to be available somewhere under the developers link on the ns.com. Where did it go?

2. I ran an xml update last night. However, something went wrong, and now I have a huge problem. It's hard to summarize the ways I've tried to get things back in order, but on the most basic level  here it goes:

After the update, catalog numbers were unintentionally shifted to other internal ID's. i.e. what was under internalID 1234 was a product named BA 10-2100. Now NS thinks that InternalID 1234 is BA 10-1900, and some other ID, call it 4321, is BA 10-2100. A nightmare actually!