Question on XSD validator

Hi All,
  Can somebody please tell me how to validate an XML document with a given XSD ?
Is the XSD validator part of an XML library [like Xerces, libxml2 etc] itself or there exist some separate library to validate an XML document using XSD ?

I am working on HP-UX11.00 with libxml2 library to parse a given XML document with an XSD. 
Any help will be highly appreciated.

Thanks in advance for the help.

With regards,
RNS
 
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