Chapter 1 Geometric Dimensioning and Tolerancing Essentials 13 Copyright Goodheart-Willcox Co., Inc. Coordinate Systems Coordinate tolerancing uses the rectangular coordinate system to locate the features of a part according to linear distances from the X, Y, and Z axes. Example 1-8 shows two of the many options for positioning the face plate in the rectangular coordinate system. The X, Y, and Z axes are implied by the orientation of the drawing views, or identified by a coordinate system icon. Adjusting the drawing views, changing the origin or orien- tation of the X, Y, and Z axes, or rotating the physical part changes the geometry in the X, Y, Z grid. The rectangular coordinate system does not define how the part should be positioned, nor does it define from where measurements are taken during inspection. See Example 1-9. A measurement taken from one surface to a specific feature differs from a measurement taken from another surface to the same feature. X axis Y axis Z axis Y axis X axis Z axis Goodheart-Willcox Publisher Example 1-8. Orthographic views showing two options for positioning the face plate in the rectangular coordinate system.