Gene, W4SZ wrote:
"No need to account for any mythical power in the reflected waves."

Cecil has an IEEE dictionary which defines power in terms of the voltage
and in-phase current passing a point.

Terman says on page 96 of his 1955 opus:
"The reflected wave is identical with the incident wave except that it
is traveling toward the generator."

Bird says of its Model 43 RF Directional "Thruline" Wattmeter:
"The forward wave travels (and its power flows) from the source to the
load. It has RF Voltage Ef and current If in phase, with Ef/If=Zo.

The reflected wave originates by reflection at the load, travels (and
its power flows) from the load back to the source, and also has an RF
voltage Er and current Ir in phase, with Er/Ir=Zo."

Best regards, Richard Harrison, KB5WZI