A technique whereby a subscriber of a multiple access communication network such as a cellular communication system is permitted to make a reservation to guarantee availability of a shared physical communication resource, such as a cellular radio telephone traffic channel, at an appointed date, time and location. The voltage source provides a regulation voltage level relative to the input node. The need to publish symbols is thereby averted and only the variables that a developer is interested in observing need be registered. The UID is used to identify the communication device, and the execution program is executed by the TV with reference to the UID. The second winding of the transformer system has an equivalent impedance at the first and second terminals based on an impedance of the transformer system and an impedance of a communication line.