As soon as it is decided to bring a new circuit into operation,the technical services of the terminal countries should agree upon the circuit control station,and the technical service of each transit country should advise the other technical services concerned of the name of the sub-control station chosen for its territory.If the circuit is routed in a direct group or block crossing a transit country without demodulation or demultiplexing,no sub-control station need be provided for the transit country.When a circuit is subjected to analogue-to-digital conversion using,for example,a transmultiplexer,the location of the transmultiplexer should be designated as circuit sub-control station.