nsgmls doesn't work

[Manuel Hernandez]

Hi all!

I'm trying to validate my HTML/XHTML documents with nsgmls. I followed
this document:

http://www.freebsd.org/doc/en_US.ISO8859-1/books/fdp-primer/sgml-primer-elements.html#AEN536

nsgmls *only* validates HTML 4.0 web pages (didn't work with my HTML
4.01 or XHTML 1.0).

I tryed to validate a docbook document of CVS:

$ cvsup -g -L 2 doc-supfile (with doc-all)

nsgmls gives me a million of errors and dind't work.

Later I found this post:

http://lists.freebsd.org/mailman/htdig/freebsd-doc/2003-November/002656.html

But nsgmls don't work neither... What is wrong? How can I do to make
nsgmls works with XHTML or docbook documents?

Example 1: Docbook document (from CVS)
$ cd /usr/doc/en_US.ISO8859-1/books/faq
$ nsgmls -c /usr/doc/en_US.ISO8859-1/share/sgml/catalog -s book.sgml

nsgmls:book.sgml:1:73:W: cannot generate system identifier for public
text "-//FreeBSD//DTD DocBook V4.1-Based Extension//EN"

nsgmls:book.sgml:3:4:E: reference to entity "man" for which no system
identifier could be generated

nsgmls:book.sgml:2:0: entity was defined here

nsgmls:book.sgml:4:91:W: cannot generate system identifier for public
text "-//FreeBSD//ENTITIES DocBook Miscellaneous FreeBSD Entities//EN"

nsgmls:book.sgml:5:8:E: reference to entity "freebsd" for which no
system identifier could be generated

Example 2: XHTML 1.0 document 
(this page was validated with http://validator.w3.org)

$ nsgmls -s /home/user/index.html
nsgmls:/usr/local/share/xml/dtd/xhtml/xhtml1-transitional.dtd:273:27:E:
omitted tag minimization parameter can be omitted only if "OMITTAG NO"
is specified on the SGML declaration

nsgmls:/usr/local/share/xml/dtd/xhtml/xhtml1-transitional.dtd:275:8:E:
character ":" invalid: only "CDATA", "ENTITIES", "ENTITY", "ID",
"IDREF", "IDREFS", "NAME", "NAMES", "NMTOKEN", "NMTOKENS", "NOTATION",
"NUMBER", "NUMBERS", "NUTOKEN", "NUTOKENS" and parameter separators
allowed

nsgmls:/usr/local/share/xml/dtd/xhtml/xhtml1-transitional.dtd:289:49:E:
omitted tag minimization parameter can be omitted only if "OMITTAG NO"
is specified on the SGML declaration

nsgmls:/usr/local/share/xml/dtd/xhtml/xhtml1-transitional.dtd:292:8:E:
character ":" invalid: only "CDATA", "ENTITIES", "ENTITY", "ID",
"IDREF", "IDREFS", "NAME", "NAMES", "NMTOKEN", "NMTOKENS", "NOTATION",
"NUMBER", "NUMBERS", "NUTOKEN", "NUTOKENS" and parameter separators
allowed

Thanks in advance and excuse this big post and my horrible English.

Regards

Manuel