As a homeowner, you should reset the opener to prevent outsiders from opening the door with a remote that's set to a Liftmaster default code. A simple procedure allows you to reset the opener for one or more remotes.
doorsill - the sill of a door; a horizontal piece of wood or stone that forms the bottom of a doorway and offers support when passing through a doorway. doorstep, threshold. 1  doorway, room access, door, threshold - the entrance (the space in a wall) through which you enter or leave a room or building; the space that a door can close; he stuck his head in the doorway.
Definition of Sill (geology) In geology, a sill is a tabular sheet intrusion that has intruded between older layers of sedimentary rock, beds of volcanic lava or tuff, or even along the direction of foliation in metamorphic rock. The term sill is synonymous with concordant intrusive sheet.