98 Geometric Dimensioning and Tolerancing Datum Target Lines A datum target line is indicated by the target point symbol “X” on the edge view of the surface and by a phantom line on the surface view. Refer to Example 3-23. If the locating pins are cylindrical, then the datum target line is along the tangency where the pins meet the part. The pins can also be knife-edged. A surface is often placed at 90° to the pin to create the datum reference frame. Fixture base The Drawing The Fixture Setup (Enlarged View) Part Locating pin Example 3-23. Specifying a datum target line.