This document specifies, with reference to ISO 230-1, the geometric tests on normal accuracy Numerically controlled (NC) turning machines and turning centres with horizontal work spindles as defined in 3.1 and 3.2. It also specifies the applicable tolerances corresponding to the above-mentioned tests. Where applicable, this document also applies to horizontal spindle turret and single spindle automatic lathes. This document explains different concepts or configurations and common features of NC turning machines and turning centres. It also provides a terminology and designation of controlled axes. 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) as such are checks generally carried out before testing the accuracy.