A method and apparatus for heating fluids with the earth’s internal energy released through the vents of the ridge expansion zones in the planet’s seas. The protocols may be used for a variety of transactions that involve two or more parties including an initiator of the transaction, a coordinator of the transaction, and one or more participants in the transaction. In the example system, the first critical section and the second critical section are merged based on a least expensive cost of merging critical sections. The first and second corresponding optical signals are converted to first and second corresponding electrical signals, respectively; and a detector, responsive to the first and second corresponding electrical signals, provides an electrical output signal from the discriminator. Conductor patterns other than the conductor portions are formed on those regions of the wiring board which the contacts at the distal end portion of the contact plate contact during the time when an arm holder is mounted on the wiring board. The controller controls an open degree of the gas turbine fuel control valve such that rapid increase of the supply of the first fuel is restrained when the supply of the second fuel to the duct burner is stopped.