In the context of controlling a radio from a computer, what does CI-V stand for? I've noticed in relationship to a jack as well as USB.
For example, from the Icom IC-7300 manual:
CI-V stands for Computer Interface 5 [Roman numeral "V"] and is ICOM's designation for their rig interface to a computer or to another rig. You can find it on most HF and some VHF rigs since the 1980s and is has not changed in it's basic structure up to now. CI-V is a simple to use interface which allows --in contrast to other manufacturers' designs-- a "daisy chaining" of rigs.
To connect just two rigs you need nothing more than a cable with two 3.5mm mini plugs. For a connection to a computer, you need an additional interface for most rigs.
Above quoted from http://www.plicht.de/ekki/civ/civ-p0.html.
The Icom CI-V interface is not a standard RS-232 type interface. The signals are TTL-level. It is a two-wire interface.
From the Icom IC-7610 Command Manual, CI-V stands for "Computer Interface V".