Legal attrubute value for ID type in a DTD?

[Andles Jurgen]

According to Wrox Professional XML the following is legal for an attribute of type ID :
<PERSON SSN="111-22-3333" />
Yet my understanding is that this ID type is that is restricted to values that are legal xml names, and therefore 'SSN' could not possibly start with the digit '1' as pro xml has stated in the above example.
Even when I tried it out - it failed to validate. I thought only NMTOKEN & NMTOKENS was free of the first character restriction on xml names.
Am I missing something here??
Andles

[Dan Drillich]

You are right. Where is it in the book?

[Andles Jurgen]

chapter 3 (DTD's), page 86 - first code sample at the top of page.

[Dan Drillich]

Which edition? I use the second edition.