NBN EN ISO 5458:1999

This International Standard describes the principle of positional tolerancing f for the location of regular and irregular features. However for clarity, only regular-shaped features such as holes, bolts, studs or pins, parallel-sided slots, keys and keyways have been shown. Positional tolerancing may also be applied to the location of a point, a straight line, or a plane surface. However, profile tolerancing must be used when lines are not intended to be straight or surfaces are not intended to lie in a plane, see ISO 1660.