Geometric tolerances like flatness, position and profile are specified on drawings using a feature control frame (FCF). The FCF gives the GD&T control instructions for a feature or group of features. A FCF is a rectangular box that is divided into compartments within which the geometric characteristic symbol, tolerance value, modifiers, and datum references are placed. The first compartment of the FCF contains one of the 14 geometric characteristics. The second contains information about the shape and size of the tolerance zone and any modifier being applied. The third, forth and fifth contain datum references if applicable.

Feature Control Frame