This command converts the entity type of LWPolylines (light-weight polylines) to Polylines. This command does not change the geometry of the polylines or any other property.
Select polylines to convert to
3D.
Select entities: pick
lwpolylines
Pulldown Menu Location: 3D Data > 2D to 3D
Polyline
Keyboard Command: lwto3dp
Prerequisite: lwpolyline