Arch
Not to be confused with wedding arch. An arch or archway is an architectural object in The Sims games. They have been present in all games, but were not placed in a separate sub-category until The Sims 2.
Arches function like doors, except that they do not have a panel which can be opened and closed. In effect, an arch is a door that is always open. In fact, many arches are simply door frames without the doors. This is particularly true in The Sims 2, where almost all Maxis-made doors have a corresponding arch.
Despite appearances, an arch appears to work as well as a door for separating one room from another, or separating the indoors from the outdoors.