Abstract: A lock which can be accommodated within the thickness of an opening panel includes two nuts rotatable about a common axis and attached to respective corresponding operating members. Each nut can turn freely about its axis relative to the other nut. The latch bolt is attached to a selector member mobile between two predetermined positions in the transverse direction corresponding to the thickness of the casing of the lock. Each nut is attached to a corresponding arrangement of the lock adapted to engage with the selection member when the latter is in its position near the nut, in order to actuate the latch bolt when the nut is turned in a first direction corresponding to retraction of the latch bolt and to remain disengaged from the selector member when the latter is in its other position near the other nut.