 This is not always the case though; for instance the output from BBC Hull, which feeds the Belmont transmitter, is actually switched at BBC Leeds, and the Channel Islands opt-out occurs at Plymouth of the UK mainland, although the programme content comes from both Plymouth and Jersey.Considerable variation can exist between the signal paths for digital (DTT and DSat) and analogue transmissions, leading to great complexity in the opt-out logic.Commercial broadcasters such as ITV, Channel 4 (with S4C) and Channel 5 distribute their programmes to regions complete with local advertising and regional programme variations.