In Geometric Dimensioning and Tolerancing (GD&T), an orientation tolerance is used to control the
parallelism, perpendicularity, or angularity of a part feature with respect to
a frame of reference (defined by the datum references). This interactive, online course discusses the three different types of orientation tolerances:
Parallelism, Perpendicularity, and Angularity and how they are communicated in GD&T.
