ISO 2768 is the international standard for general tolerances used in mechanical engineering to simplify technical drawings by defining default precision levels for dimensions and features. Instead of specifying an individual tolerance for every single length, angle, or geometric feature, designers can reference a single class (e.g., ISO 2768-mK) in the drawing's title block to establish a "standard workshop accuracy" for the entire part.
Given a , tolerance class (f, m, c, v), and type of dimension (linear, external radius, chamfer height, or angular), the tool automatically outputs the standard tolerance value as defined in ISO 2768-1 (for linear/angular) and ISO 2768-2 (for geometrical tolerances). Iso 2768 General Tolerances Pdf