This Standard establishes methodology for specifying and testing the performance of Computer Numerically Controlled (CNC) machining centers. In addition to clarifying the performance evaluation, this Standard facilitates performance comparisons between machines by unifying terminology, general machine classification, and the treatment of environmental effects. It provides a series of tests that should be used to perform acceptance testing (runoff) of new and reconditioned machines and could be used to verify continued capability of production machines, already in operation, through periodic testing. The set of acceptance tests and the specification limits for machine conformance shall be the subject of contractual agreement between the Supplier and the User. This Standard is rather comprehensive; therefore, for smaller and less expensive machines the conformance to specifications could be based on a recommended subset of tests to evaluate machine performance.