Withdrawn Standard. Withdrawn Date: Dec 06, 1990. This standard applies to electrothermic power meters as complete instruments and to their constituent parts: electrothermic elements, electrothermic units, and electrothermic power indicators. Electrothermic power measurement instrumentation is generally used to measure (below 3 W and above 2 MHz) the average power of an electromagnetic wave propagating in a single mode in waveguide or coaxial transmission lines. The power range can be extended by the use of attenuators or directional couplers, or both.