First of all, CBMP is a FOOT POSITION. The letters stand for Contra Body Movement Position (American; in International the C may stand for "contrary"). Here are two definitions from books I have:
1. The placing of the stepping foot, forward or back, onto or across the line of the other foot, giving the appearance of CBM having been used, but without turning the body.
2. ... is the position attained when either foot is placed across the front or the back of the body without the body turning. It is, therefore, a foot position, ...
These definitions are essentially the same. In essence, CBMP is the result of a foot movement that causes the feet and the body to be in more or less the same relationship that results from CBM (contra body movement, which is the result of doing something with the body).
This may look pretty abstract but it becomes clear when you do it.