This part of ISO 10303 specifies the resource constructs for the representation of 2D modelling commands for use in the exchange of procedurally represented 2D CAD models. A procedural model is defined in terms of the sequence of 2D modelling operations used to build it. The following are within the scope of this part of ISO 10303: — entities representing creation commands for geometric elements such as lines, arcs, chamfers and fillets; — entities representing transformation operations such as rotations and translations. The following are outside the scope of this part of ISO 10303: — the identification of selected entities by interactive picking in a procedural model; — the specification of sequences of modelling commands; — query, deletion and modification commands (except in the case where the modification is a transformation); — dimensioning and constraining commands for 2D modelling. The first and second capabilities in the out of scope list above are provided by ISO 10303-55, and the fourth by ISO 10303-108. This part of ISO 10303 is designed to be used in conjunction with those parts of ISO 10303.