1. W3C, 2004, Extensible Markup Language (XML) v1.0, http://www.w3.org/TR/REC-xml.
2. ISO 10303-1:1994, Industrial Automation Systems and Integration—Product Data Representation and Exchange-Part 1: Description Methods: Overview and Fundamental Principles.
3. Kemmerer, S., ed., 1999, STEP: The Grand Experience, National Institute of Standards and Technology, NIST SP 939, http://www.mel.nist.gov/msidlibrary/publications.html.
4. Object Management Group, 2003, OMG Unified Modeling Language Specification v1.5, http://www.omg.org/technology/documents/formal/uml.htm.
5. ISO/IEC JTC1/SC34 N0029, 1998, Document Description and Processing Languages–Final Text of Revised TC2 to ISO 8879:1986, http://www.y12.doe.gov/sgml/sc34/document/0029.htm.