George,
I think that is where some people get confused. A "multiwire circuit" is, for example, a range outlet. It has to be fed with a multipole breaker, on different phases, which opens the two circuits simultaneously. These of course have to be side by side.
A "multiwire branch circuit" is more than one circuit, of different phases, sharing a neutral. For example, general purpose lighting and receptacle loads. These do not have to be side by side in the panel, and do not have to be opened simultaneously.
