A feature control frame consists of at least two compartments. The first contains a geometric characteristic symbol, which represents the geometric characteristic to which a tolerance is being applied, for example, form, orientation, or runout. Form tolerances control straightness, flatness, circularity, cylindricity, and profiles of line and surface. In the illustration, the characteristic is position.
The second compartment contains the tolerance value. Depending on the control type, the tolerance value is preceded by a diameter symbol and followed by a material condition symbol.
For a full table of geometric characteristics and their symbols, see the example.
Example: Geometric Characteristic Symbols