ISO/TS 10303-1275:2004 specifies the application module for External class.
The following are within the scope of ISO/TS 10303-1275:2004:
- The identification of a class that is external to a data exchange file;
- The identification of an external class library that is not in an exchange file and holds the definition for classes used in the exchange file;
- A reference to a class in an external class library.