1. International Standards Organization (ISO). 2002. “ISO/WD 10303-28 Product data representation and exchange-Implementation methods: XML Schema governed representation of EXPRESS schema”. ISO TC184/SC4/WG11 N195
2. International Standards Organization (ISO). 2003a. “ISO/WD 10303-28 Product data representation and exchange-Implementation methods: XML Schema governed representation of EXPRESS schema governed data”. ISO TC184/SC4/WG11 N223 Version2
3. International Standards Organization (ISO). 2003b. “ISO/DIS 14649-12 Industrial automation systems and integration – Physical device control – Data model for Computerized Numerical Controllers: PROCESS DATA FOR TURNING”. ISO TC184/SC4/WG7 N000 Version14. Available online at:http://www.steptools.com/library/stepnc/tech_resources/Part12_V14_20031022.pdf(accessed 2 May 2005)
4. International Standards Organization (ISO). 2003c. “ISO/DIS 14649-121 Industrial automation systems and integration – Physical device control – Data model for Computerized Numerical Controllers: TOOLS FOR TURNING MACHINES”. ISO TC184/SC4/WG7 N000 Version9. Available online at:http://www.steptools.com/library/stepnc/tech_resources/Part121_V9_20030719.pdf(accessed 2 May 2005)