Where an angular surface is defined by a combination of a directly toleranced linear and an angular dimension, the surface must lie within a tolerance zone represented by two nonparallel planes. See Fig. 2-18. The tolerance zone will widen as the distance from the apex of the angle increases. Where a tolerance zone with parallel boundaries is desired, angularity or profile tolerance may be used. See Fig. 6-1 and Sections 6 and 8.