ISO/TS 10303-1779:2014-02 specifies the application module for
External representation item.

The following are within the scope of
ISO/TS 10303-1779:2014-02:

• definition of an element of a representation whose value is not included in the data exchange file and is defined in an
  external dictionary;
• items within the scope of application module External library, ISO/TS 10303-1778;
• items within the scope of application module Foundation representation, ISO/TS 10303-1006.