To Add or Modify a Dimension
1. Select one or two entities as references and then click > 
Dimension. A default dimension appears.
Dimension. A default dimension appears. | Dimension commands are also available on the Annotate tab. |
2. To select a different dimension option, right-click and choose one from the shortcut menu.
3. To remove a selected reference, hold down the CTRL key and reselect the reference.
4. Middle-click to place the dimension and middle-click again to exit the tool.
5. To edit the value of a dimension, select the dimension and then right-click and choose Edit Value from the shortcut menu. Type a new value and press ENTER. The entity updates.
6. To override the value of a dimension without updating the entity, select the dimension and then right-click and choose Properties from the shortcut menu. The Value Display dialog box opens.
Select Override Value and type a new value in the box and click OK.
7. To lock or unlock a dimension, select the dimension and then right-click and choose Lock or Unlock from the shortcut menu.
8. To modify the style of the text, select the dimension and then right-click and choose Text Style from the shortcut menu. The Text Style dialog box opens. Set the style and click OK.