The 2-Model Machining process group introduces two GCDs that are extracted in addition to the other GCDs used in the Machining cost model:

The 2-Model Machining process group also introduces a new property “Is Stock Surface” for planar face, curved wall, and curved surface GCDs.

For information about machining GCDs that are not specific to 2-Model Machining, see Stock Machining and Machining Process Groups on page 471.