Profile tolerances can control the location, orientation, and form of a feature that has no size (sur-
face). There are two (2) types – profile of a surface (∩) and profile of a line (∩). The exact or true
profile of a feature is established by basic dimensions of radii, angular dimensions, and coordinate
dimensions established from datums however a profile tolerance can be specified to an individual
surface without specifying a datum – see Fig. 16. The elements of a profile (outline of an object
in a given plane) are straight lines or arcs. The tolerance is a boundary of two (2) parallel planes
disposed (equally – see Fig. 17 or in one direction – see Fig. 16) and normal (perpendicular) along
the perfect or true profile within which the entire surface must lie. The profile can be controlled
between two (2) points – see Fig 16. Also if datum planes are established by targets – see Fig. 18
the tolerance zone is equally disposed about the datum planes whereas if the datum planes are
established by complete contact with the datum features the tolerance zone is unidirectional and
½ the tolerance value in the FCF – see Fig. 17 vs Fig. 18.