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.
Mullion. A mullion is a vertical element that forms a division between units of a window, door, or screen, or is used decoratively.When dividing adjacent window units, its primary purpose is to provide structural support to an arch or lintel above the window opening.ts secondary purpose may be as a rigid support to the glazing of the window. When used to support glazing, they are teamed with horizontal supporting elements called transoms. In the commercial door industry, the term is also applied to a piece of hardware that divides the opening of a pair of doors.