Bob, there certainly are coaxial cables with RCA plugs on them, and it would be fair to call them "RCA cables". The term is often used however to refer to a less expensive cable not of the shielded 75 ohm coaxial variety, which can make things confusing. No, a "digital" cable(strictly speaking no such thing exists since any conductive metal can handle either analog or digital signals, over at least short distances)doesn't necessarily have to be a 75 ohm coaxial cable. For example, up to about 40 feet, digital CD output works fine over an "analog" cable. Longer than that(and shorter distances for HDTV), a 75 ohm coaxial cable should be used.
