Measuring With Datums: Location Tolerance

Location tolerance determines the location (true position) of the feature in relation to a reference.
As this involves measurement of a three-dimensional feature, it is difficult to use calipers, micrometers, or any other instrument that measures the distance between two points for accurate measurement.

A datum is always necessary to indicate location tolerance; as such, it is a geometric tolerance for features related to datums.

Measuring With Datums 2: Location Tolerance