A & B in MEPs

Currently in the MEPs spec the first message sent in a MEP is called A and
the second is called B. This pattern is used both for in-out and out-in
style MEPs. While the usage is completely consistent it could be made
slightly more friendly were the messages to be named A-IN B-OUT (or
something similar) in the case of an in-out pattern and A-OUT and B-IN in
the case of a out-in pattern. This naming convention also has the benefit of
being a little harder to lose in the text. After all, 'A' in particular has
a habit of becoming 'a' which then just makes sentences confusing.

	Thanks,

			Yaron