Select edges without completing a face

The option to select edges that form a closed shape without completing the face.

This is useful when assigning a different material to beveled areas for faces with edges selected on all sides: e.g.)

Starting with the default cube, create two materials for it (green and blue), assign blue to the main cube, select three edges on the top of the cube, use the Bevel tool, assign green (green will only assign to the beveled areas).

Now do the same, except -- this time -- select all four edges on top of the cube. Because four edges complete a face, assigning green to the cube will assign it to the entire cube. Green will overwrite all blue areas, which is not what we want.