In a mechanical drawing of a part, angularity tolerance allows the designer to specify the degree to which the orientation of an angled part feature may vary. The angularity symbol is often used to insure that the part can properly mate with another. In GD&T, the degree of permissible variation is not specified as a tolerance on the angle. Rather an indirect method is used where one specifies a tolerance zone at a specified angle from a datum, within which a part feature, axis, or center plane must lie.