xml.dcl error

Denis pointed the new install manual to the 4.2 XML spec; and I
installed the unstable version of docbook-xml to get it.

Now, nsgmls is giving me an error:

nsgmls:/usr/share/sgml/declaration/xml.dcl:31:27:W: characters in the document 
character set with numbers exceeding 65535 not supported

This refers to a line that is supposed to handle that case.  Do I need
to upgrade something else not in the dependency list?

-- 
Debian GNU/Linux Operating System
By the People, For the People
Chris Tillman (a people instance)