ISO/TS 10303-1651:2006 specifies the application module for Basic curve.
The following are within the scope of ISO/TS 10303-1651:2006:
the representation of a curve that is the result of trimming another curve;
the representation of a curve that is the result of combining other curves;
the representation of a closed curve;
the representation of a boundary curve;
items within the scope of application module Basic geometry, ISO/TS 10303-1652;
items within the scope of application module External item identification assignment, ISO/TS 10303-1128.