In an interface structure comprising a first assembly and a second assembly wherein the first assembly includes a cavity having a truncated cone-like section, a stop surface effective in the axial direction and a second assembly including a trunnion with a truncated cone-like section for abutment on the truncated cone-like sleeve section of the first assembly and an abutment surface for contacting the abutment surface of the first assembly, between the cavity and the trunnion a bayonet-like locking structure is provided in the interface structure whereby handling with a high repetition accuracy with regard to the position of the assemblies to be joined is ensured.