Unit 9 Dimensioning 183 Copyright Goodheart-Willcox Co., Inc. model, Figure 9-20. The views are not required to provide a complete product definition, although that is allowed. Requirements for creating a data set that uses both a model and a drawing graphic sheet include the following: • Product definition data created or shown in the model must be in agreement with the drawing graphic sheet, and vice versa. • The drawing graphic sheet must include a border and title block. Hard copy outputs must be obtainable. • When complete product definition is not contained on the drawing graphic sheet, it must be noted. • When complete product definition is not contained on the model, it must be noted. • Dimensions, tolerances, datums, and notes may appear in orthographic views or axonometric views. • The use of color is acceptable on drawing graphic sheets. Undimensioned Drawings The ASME Y14.31 Undimensioned Drawings stan- dard was developed to set forth recommendations for drawings that describe the size of an object without annotations, much as if the drawing itself were a size template or overlay. By definition, an undimensioned drawing defines the item with a true geometry view. The true geometry view serves as a true profile of the part. Within this system, drawings are usually printed or plotted full scale on a strong and durable media, such as polyester film. While some dimensions may be included, they are usually of a nominal reference nature, or for features held to tolerances different from the undimensioned feature tolerances. Undimensioned drawings are suitable for applications such as parts with numerous irregular contours, printed circuit boards, wire harnesses, flat patterns, art layout for instruction plates, and formed sheet metal sections. Undimensioned drawings must incorporate dimensional accuracy methods so that the accuracy of the drawing can be verified as true size. Acceptable methods could include grid lines, dimensional accuracy points, or registration marks. Goodheart-Willcox Publisher Figure 9-19. Some companies are now incorporating digital product definition, wherein the 3D model provides most of the size information, but critical dimensions and annotations can still be added.