The command prompts you to select a centerline. If none exist, it draws a centerline as you pick points. The command mirrors the polyline segments about the centerline as you draw.
List of Prompts
The following prompts are displayed.
Select Centerline or new starting point
Specifies an existing centerline to use as the line of symmetry. or inserts the starting point for a new a centerline
New starting point
Specifies the starting point to draw a new centerline.
Centerline endpoint
Specifies the end point of the centerline
Start point
Begins drawing the polyline that is to be mirrored about the selected centerline. Subsequent prompts are identical to that of the PLINE command. Please refer help on the PLINE command for details.