the attachment plate has a rectangular planar front wall with two groups each with three mounting sites . these groups are used for mounting sanitary fixtures such as for example isolating valves and the like . the two groups have in each instance two mounting sites disposed on a straight line . each group has moreover at least one third mounting site at a distance one from the other which is different from the distances of the remaining mounting sites . the mounting sites are disposed in such a manner on the attachment that all commonly used sanitary fixtures and the like can be mounted .