Abstract: A group of networked elements for controlling the equipment of a building, when the elements are in a learning mode, can be assembled by a pair of actions. The first action exerted by an installer on one of the elements should be interpreted as an interrogation concerning the state of membership in the group (for example, as included or excluded) of one of the elements of the group. The first action triggers the emission of an information signal regarding the identified element's state. The following, or second, action exerted on the chosen element is interpretable as an order for modifying the state of membership in the group of the chosen element.

Abstract: A speed reducer is contained in a modular housing that includes a body having a chamber for mounting the gear train and power shafts and which is open at two opposing ends, an end member for mounting the speed reducer and forming an oiltight seal with the body at one of the ends, and another end member forming an oiltight seal with the body at the other of the ends.