Select a line or edge

When you start the Smart Dimension command, the program prompts you to select an entity.
As soon as you select an entity, the options in the selection list change, depending on the point at which you select the entity: If you select a line or edge, the selection displays the following options:
Orientation Enables you to specify the orientation of the dimension line. Select one from the drop-down list
Type Enables you to specify the type of the dimension to be created, based on the selection you performed. Select one type from the drop-down list
Properties Displays the Properties dialog box


You can then create a linear or angular dimension using one of the following options (to be selected in the Type drop-down list):
Line Length You can specify the orientation as one of the following:
Distance parallel to the line through the endpoints of the entity
Horizontal parallel to the X-axis
Vertical parallel to the Y-axis
Projected projected at a specified angle
Point & Line
Half View
Angular
Parallel
In addition to these options, if you move the cursor over another non-parallel line or edge, the command switches into angular mode and you can insert an angular dimension.