This part of ISO 230 is aimed at standardizing methods of specification and test of the geometric accuracy of axes of rotation used in machine tools. Spindles, rotary heads and rotary and swivelling tables of machine tools constitute axes of rotation, all having unintended motions in space as a result of multiple sources of errors. This part of ISO 230 covers the following properties of spindles: ? axis of rotation error motion; ? speed-induced axis shifts. The other important properties of spindles, such as thermally induced axis shifts and environmental temperature variation-induced axis shifts, are dealt with in ISO 230-3. This part of ISO 230 does not cover the following properties of spindles: ? angular positioning accuracy (see ISO 230-1 and ISO 230-2); ? runout of surfaces and components (see ISO 230-1); ? tool holder interface specifications; ? inertial vibration measurements (see ISO 230-8); ? noise measurements (see ISO 230-5); ? rotational speed range and accuracy (see ISO 10791-6 and ISO 13041-6); ? balancing measurements or methods (see ISO 1940-1 and ISO 6103); ? idle run loss (power loss); ? thermal drift (see ISO 230-3).