Actually Jax2, from a purely technical standpoint you are right. All RCA connections are a "coaxial type" connection.
The term is only used to decribe the digital output connection. I guess we assume people are not talking about other RCA outputs which in addition to the audio output include tape-out and pre-out.
I have seen the term "RCA coax" in owners manuals, used for audio outputs on some old foreign gear that also had DIN plug outputs. Today the term "single ended" is usually used to denote an RCA output versus a "balanced" (DIN) output.
