|1.||(communications)||out-of-band - The exchange of call control information on a dedicated channel, separate from that used by the telephone call or data transmission.|
|2.||out-of-band - Sometimes used to describe what communications people call "shift characters", such as the ESC that leads control sequences for many terminals, or the level shift indicators in the old 5-bit Baudot codes.|
|3.||out-of-band - In personal communication, using methods other than electronic mail, such as telephone or snail-mail.|
|4.||(software)||out-of-band - Values returned by a function that are not in
its "natural" range of return values, but rather signal some
kind of exception. Many C functions that normally return
a non-negative integer return -1 to indicate failure.|
This use confuses "out-of-band" with "out-of-range". It is actually a clear example of in-band signalling since it uses the same "channel" for control and data.
Compare hidden flag, green bytes, fence.