In this correspondence, the concept of a test schema which describes how a test methodology is to execute is introduced. We also introduce the powerful concept of an I path which is used to transfer data unchanged from one place in a circuit to another. The process of embedding a test schema into an actual circuit is described. This produces a test plan for the circuit which specifies the sequence of actions that need to be carried out to execute the test. A theory of test plan execution overlap is presented, and is used as the basis for constructing test schedules with optimal execution times.