The invention relates to door or window fittings, a base plate (10) and detent elements (18). The base plate and/or detent element is/are used to fix an operating element (door latch, handle, knob etc.) or a pair of operating elements on a door or window. The base plate is essentially characterised by a first surface (14) that defines an axis and acts as a guide surface for receiving bearings of different operating elements, the first surface running from a lower end that faces the door or window surface to an upper end. In addition, the base plate (10) has a second surface (16), which tapers from the exterior towards the upper end of the first surface (14), in relation to the axis. The inventive detent element is configured in such a way that it can be used for operating elements, in which the conical section at the end of the neck of an operating element is extremely short. The detent element is configured as a disc comprising at least one recess that reduces the width of said disc.