Mortise Style locks fit inside the door panel. The Mortise
lock is Independent of the handle.
This style of door handle allows many options for
exterior trim. The most common screw hole spacing is 3-
15/16". However, many are interchangable.
The picture below is an example of a mortise style
sliding glass patio door lock. The difference between this type
and the surface mount hook type patio door
handle sets is that the mortise type has a lock body
which mounts inside the door itself.