channels described above as well as the devices for connecting to adjacent modules it should be pointed out here that this u201c incorporation u201d into the overall system naturally also applies to the water tank 58 and the waste water tank 59 and that such tanks can also serve as extra tanks for fuel the important thing here is that a simplified assembly outside the aircraft to form a unitary module which in some cases includes an associated partition 54 is thereby made possible the floor modules thus constitute firstly u201c functional subassemblies u201d that comprise special equipment for transporting and securing freight or electronic components ee rack or tanks on the other hand the floor modules also constitute u201c passageways u201d which serve only to provide a passage for e g air conditioning conduits 29 fig6 that has no special direct function in this section of the cargo compartment furthermore it is also possible as shown in fig7 to mount lining elements 62 on the floor modules 50 by way of mounting devices 63 in which case preferably additional guide rails or similar guide means are fastened to the outer skin of the aircraft within the cargo compartment in such a way that the floor modules can be transported into the cargo compartment together with the lining elements it will be evident from the above that it is an essential basic idea of the invention for the cargo compartment floor to incorporate its carrying structures and as many as possible of the other functional elements.