The ITU Radiocommunication Assembly, considering that conventional methods of propagation are inadequate in an underground or confined environment; that the use of leaky feeder systems is established as a solution to those propagation problems; that all types of mobile radio service may require communications in these environments; mobile service over a wide range of frequencies in the HF, VHF and UHF frequency bands; that systems using the leaky feeders and related techniques have now been in use for many years in the land.