Use this procedure to center any of the following between two points: architectural objects, hatches, lines, polylines, arcs, circles, AEC polygons, mass element extrusions, spaces, or any block-based content (including detail components) made up of these types of linework or objects.
- Select the linework, object or block to center.
- Click
. 
- Select an existing edge as an axis, and then specify two points between which to center the object on that axis; or press Enter, and specify any two points between which to center the object.