Measuring With Datums: Orientation Tolerance

Orientation tolerance is a geometric tolerance that determines the orientation for the form in relation to a reference.
The parallelism, perpendicularity, and angularity of two lines or two planes are measured using a datum plane as a reference. This can also be measured using a height gauge or square ruler.
Using a coordinate measuring machine, targets of a size difficult to measure with a height gauge or ruler, as well as positions that are difficult to measure with these tools, can be measured by taking advantage of the mobility of the stylus.

Measuring With Datums 1: Orientation Tolerance