96 Geometric Dimensioning and Tolerancing Datum Target Areas Areas of contact can also be used to establish datums. When this is done, the shape of the datum target area is outlined by a phantom line with section lines through the area. Circular areas are dimensioned with basic or tolerance dimensions to locate the center. The diameter of the target area is provided in the upper half of the datum target symbol, as shown in Example 3-21, or with a leader and dot pointing to the upper half. The locating pins for target areas are flat end tooling pins with the pin diameter equal to the specified size of the target area. The Drawing The Fixture Setup (Enlarged View) Fixture base 3X ∅12 locating pins X1,∅12 X3,∅12 X2,∅12 Datum feature Part Datum plane X Example 3-21. Datum target areas are located to their centers. The locating pins for target areas are fl at end tooling pins with the pin diameter equal to the specifi ed size of the target area.