The following compilation lists a few web sites that are relevant to schema definition in XML.

• http://www.w3.org/

  The World Wide Web Consortium (W3C) is the reference point for the XML specification (i.e. DTDs) and XML Schema.

• http://www.xml.org/ (hosted by OASIS)

  is a repository for XML schemas.

• http://www.xfront.com/

  discusses programming techniques for schema authors.

• http://www.xmlpatterns.com/

  contains a collection of design patterns for XML.

• http://www.aomodeling.org/

  is the home of Asset Oriented Modeling.