Assemble by Edge and Point

Changes the position of an object by changing the location and alignment of an edge. You can also add a source point and destination point to change the rotation as well.
To assemble by a pair of edges:

Select the object to be repositioned.
Select the source edge. The new alignment of the edge depends on where you select the edge; the point you select will be moved to the point you select on the destination edge.
Select the destination edge. The dotted lines indicate how the object will be aligned.
Select Finish from the local menu or Inspector Bar. The object is moved so that its source edge meets the destination edge, connected at the two selected points.

To assemble by edges and a plane:
Select the object to be repositioned.
Select the source edge. The new alignment of the edge depends on where you select the edge; the point you select will be moved to the point you select on the destination edge.
Select the destination edge. The dotted lines indicate how the object will be aligned.
Select a point on the source plane (not on the selected edge) and a point on the destination plane.

The object is moved so that its source edge meets the destination edge, connected at the two selected points. The rotation is set by the points on the source and destination planes. The results are shown here in Hidden Line render mode.