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Datum (#): A theoretically point, axis, or plane from which you make measurements and verify dimensions. Usually, two or three mutually perpendicular planes perform this task best. These are jointly called the datum reference frame. Specify one of three datum references - primary, secondary, and tertiary (A, B, and C). The datum reference can consist of a value and a modifying symbol.HAnchor
Height Protected Tolerance Zone:* Controls the variation in height of the extended portion of a fixed perpendicular part and refines the tolerance to that specified by positional tolerances. Enter a value in the data entry field. A projected tolerance zone symbol (P) can be inserted or discarded by toggling the box succeeding the height entry field.Use the *Format page to set the parameters for the lines and text of the Tolerance.To edit a tolerance symbol, open its Properties window (see Object Properties) and click Tolerance.