Computer controlled or “numerically controlled” co-ordinate measuring machines (CMM), or dimensional inspection machines, having a three dimensional (volumetric) maximum permissible error of indication (MPP E ) at any point in the operating range of the machine (i.e. within the length axes) equal to or less (better) than (3 + L/1 000 ) μm (L is the measured length in mm), tested according to ISO 10360-2 (2001), and measurement probes designed therefor.