[xml] periods legal in an NMTOKEN

["David Cramer" <dcramer broadjump com>]

We have a dtd with attributes defined as NMTOKEN. When the attribute
values have periods in them, we get the error:

"validity error: standalone: foo on bar value had to be normalized based
on external subset declaration"

Our processing system is designed to die on the word error (some other
xsl processors aren't so nice with their exit codes). If I change
NMTOKEN to CDATA in the DTD, we no longer get the error but that causes
other problems. 

Looking at the spec, I think periods should be ok in an NMTOKEN:

http://www.w3c.org/TR/2000/REC-xml-20001006#NT-Nmtoken

Thanks,
David