284 Geometric Dimensioning and Tolerancing Copyright Goodheart-Willcox Co., Inc. Orthographic View Meaning 8.8 MMC 1.5H 0.8H H = Letter height Symbol Specifications Datum plane A 0.2 Wide parallelism tolerance zone Two parallel planes parallel to datum plane A 8.2 LMC Model View Tangent plane A plane contacting the high points of the actual surface Actual surface Goodheart-Willcox Publisher Example 7-3. Using a tangent plane in a parallelism tolerance application.