On Mortise Locks, we do not prepare the bore on the face of door, or the lock preparation on the jamb.
We only prepare the side of the slab.
Backset: The measurement from the edge of the door to the center of the pre-drilled hole.
Cross Bore: A hole drilled into the face of a door where a bored or interconnected lockset is to be installed.
Edge Bore: The hole bored through the edge of a door to allow the latch to pass through, into the strike.