How can you distinguish between a datum symbol and a datum target on a drawing?

How can you distinguish between a datum symbol and a datum target on a drawing?

• A. A datum target is a circled letter marking the datum.
• B. The datum symbol is the circled letter, while a datum target shows where the datum is established on a surface.
• C. Datum symbol and datum target are the same thing.
• D. A datum target marks the datum on the face with arrows.

Answer: (B)

The main idea is that the datum symbol and the datum target serve different roles in GD&T. The datum symbol is the circled letter that names the datum reference—the label that identifies which feature is being used as the datum. The datum target, on the other hand, marks the exact location on the part surface where that datum is established, usually connected to the surface by a leader line. On a drawing you’ll see the circled datum letter as the label, and you’ll also see separate target markers on the surface indicating where the datum is defined. This distinction matters because a datum is a defined reference frame, while the target shows the precise spot or region on the part that defines that reference. So the circled letter identifies the datum, and the datum target shows where on the surface the datum is established.

The main idea is that the datum symbol and the datum target serve different roles in GD&T. The datum symbol is the circled letter that names the datum reference—the label that identifies which feature is being used as the datum. The datum target, on the other hand, marks the exact location on the part surface where that datum is established, usually connected to the surface by a leader line. On a drawing you’ll see the circled datum letter as the label, and you’ll also see separate target markers on the surface indicating where the datum is defined. This distinction matters because a datum is a defined reference frame, while the target shows the precise spot or region on the part that defines that reference. So the circled letter identifies the datum, and the datum target shows where on the surface the datum is established.