xml changed file validation

[Tom Bullock]

Developers,

Documentation instructions require that xml module changes be validated 
before  building a patch.

Reading the README file for 
http://svn.gnucash.org/repo/gnucash-docs/trunk/ I see that "GnuCash-docs 
is written using docbook-xml, using xml (not sgml).

In that file 'xmlto' is mentioned for the purpose of converting to other 
formats (such as to PDF or HTML files).  But no mention of XML validation.

In the wiki for translating the GnuCash Guide & Help files there is the 
instruction to that "xml file has no syntax errors"  and it indicates 
using the command:  "xmllint --valid --noout  gnucash-guide.xml"

This instruction assumes the reader knows the context of that command 
and how it is setup and works.   When I google 'xmllint' I get lots of 
references.  Since I want to validate just my changes, I should replace 
'gnucash-guide.xml' with the name of my changed module, correct?  I 
don't need to validate what I am not changing, correct?

I have also been looking at what google returns when searching for Open 
Source XML validators.  Has anyone any experience with this free editor?:
http://xml-copy-editor.sourceforge.net/index.php?page=ubuntu

Thanks for any and all responses.

Tom