This part of ISO 230 specifies methods for testing and evaluating the accuracy and repeatability of positioning of numerically controlled machine tool axes by direct measurement of individual axes on the machine. These methods apply equally to linear and rotary axes.When several axes are simultaneously under test, the methods do not apply.This part of ISO 230 can be used for type testing, acceptance tests, comparison testing, periodic verification, machine compensation, etc.The methods involve repeated measurements at each position. The related parameters of the test are defined and calculated. Their uncertainties are estimated as described in ISO/TR 230-9:2005, Annex C.Annex A presents the estimation of the measurement uncertainty.Annex B describes the application of an optional test cycle: the step cycle. The results from this cycle are not to be used either in the technical literature with reference to this part of ISO 230, nor for acceptance purposes, except under special written agreements between manufacturer/supplier and user. Correct reference to this part of ISO 230 for machine acceptance always refers to the standard test cycle.Annex C contains considerations related to periodic positioning error.Annex D describes tests using ball array and step gauge.