Every routing specifies a sequence of processes or operations. A process routing specifies a sequence of processes that can be used to produce a part. An operation sequence specifies a sequence of operations that can be used to produce a given type of GCD. Process routings and operation sequences have one node for each process or operation; they can also have additional nodes, branch nodes, which stand for subsequences consisting of processes or operations.

A template defines a collection of alternative process routings or operation sequences. As with process routings and operation sequences, process and operation templates have nodes that represent processes or operations, and have branch nodes that represent subsequences consisting of processes or operations. But templates also have another type of branch node with a different purpose—to represent a group of processes or operations that are alternatives to one another. In this way, a template represents a set of alternative process routings or operation sequences.

This section has the following subsections: