1. Click Home tabAnnotation panelDimension Style. Find
2. In the Dimension Style Manager, select the style you want to change. Click Modify.
3. In the Modify Dimension Style dialog box, Symbols and Arrows tab, under Center Marks,
   click Line.
4. In the Size box, enter the length of the centerline overshoot. Click OK.
5. Click Close to exit the Dimension Style Manager.

The example area in the dialog box displays the results of your changes.

Learning AutoCad