Keith wrote:
"I am surprised that a book on optics would discuss the output impedance
of Thevenin`s equivalent circuits."

Hecht is a physicist.

On page 74 of Terman`s 1955 0pus, he writes:
"According to Thevenin`s theorem, any linear network containing one or
more sources of voltage and having two terminals behaves, in so far as a
load impedance connected across these terminals is concerned, as though
the network and its generators were equivalent to a simple generator
having an internal impedance Z and a generated voltage E, where E is the
voltage that appears across the terminals when no load is connected and
Z is the impedance that is measured between the terminals when all
sources of voltage are short-circuited."

On page 87 of his 1955 opus, Terman writes:
"The vector ratio of E2/E1 of the voltage of the reflected wave to the
voltage of the incident wave at the load is termed the "reflection
coefficient" of the load."

On page 97, Terman writes:
"The standing-wave ratio S is one means of expressing the magnitude of
the reflection coefficient;"

On page 214 of "Schaum`s Outline of College Physics", Bueche & Hecht
write:
"Standing waves---These might better not be called waves at all since
they do not transport energy and momentum.---"

Cecil is vindicated.

Best regards, Richard Harrison, KB5WZI