Dimensioning a Drawing - AutoCAD 2011 and AutoCAD LT 2011: No Experience Required - page 612

This is where you will set up the feature control frame. The black
squares will contain symbols, and the white rectangles are for toler-
ance or datum values or for reference numbers.
FiGuRE 12.16 The Geometric Tolerance dialog box
2. Click in the top Sym box on the left to open the Symbol dialog box,
which contains 14 standard symbols that describe the characteristic
form or position for which the tolerance is being used.
When you select one of the symbols, the window closes, and the
symbol is inserted into the SYM box. Click the icon in the top row
that consists of two concentric circles, as shown in Figure 12.17.
FiGuRE 12.17 The Symbol dialog box
3. Click the top-left black square to the left of the Tolerance 1 text box.
This inserts a diameter symbol.
4. Click the top-right black square to the right of Tolerance 1. The
Material Condition dialog box (see Figure 12.18) opens and displays
the three material condition options.
When you click one, it's inserted in the top-right square of
Tolerance 1.
If you need them, you can insert any of these three symbols in
Tolerance 2 and Datum 1, 2, or 3.