This document specifies, with reference to ISO 230‑1 and ISO 230‑7, the geometric tests for general-purpose normal accuracy numerically controlled (NC) turning machines and turning centres with vertical workholding spindles, as well as the corresponding applicable tolerances. This document explains different concepts or configurations and common features of NC turning machines and turning centres with vertical workholding spindles. It also provides a terminology and designation of controlled axes (see Figures 1, 2 and Table 1). This document deals only with the verification of the accuracy of the machine. It does not apply to the operational testing of the machine (e.g. vibration, abnormal noise, stick slip motion of components) nor to machine characteristics (e.g. speeds, feeds). Tests not concerning the geometric accuracy of the machine are dealt with in other parts of ISO 13041.