True position

Related terms

GD&T

GD&T is geometric dimensioning and tolerancing, the symbol system defined in ASME Y14.5 and ISO 1101 for controlling the form, orientation, location, and runout of part features relative to datums. It states functional intent more precisely than plus-minus dimensions and often allows larger tolerances where they do not matter.

Datum

A datum is a theoretically exact point, axis, or plane, established by a real feature on a part, from which other features are located and measured. Drawings list datums in order of precedence (primary, secondary, tertiary), which tells inspection how to fixture the part.

Maximum material condition

Maximum material condition is the state where a feature of size contains the most material allowed by its tolerance: the smallest hole or the largest pin. When a position tolerance is applied at MMC, the tolerance grows as the feature departs from MMC, which is called bonus tolerance.