Please, redirect my question where appropriate: Errors on http://www.w3.org/TR/1999/REC-html401-19991224/strict.dtd?

Hello, I'm writing to you with respect to a validation problem on http://www.w3.org/TR/1999/REC-html401-19991224/strict.dtd
I am working on some legacy web services (in particular, the WS-I SCM  
use case), and the when trying to marshal the schemas used by these WS  
errors are reported on the mentioned file.
JAXB xjc tool reports:

[ERROR] The declaration for the entity "ContentType" must end with '>'.
   line 81 of http://www.w3.org/TR/1999/REC-html401-19991224/strict.dtd

and your own validator (http://www.w3.org/2001/03/webdata/xsv) reports:

Error: Syntax error after <!
  in unnamed entity at line 78 char 3 of http://www.w3.org/TR/1999/REC-html401-19991224/strict.dtd

Perhaps this file is not supposed to be validated as a schema. Anyhow,  
this is causing me a lot of inconveniences.
Is there an alternative schema to substitute this dtd?, do you know of  
some workaround?.
Thanks in advance, and best regards,
                                                            Juan Pedro  
Silva