CBMP stands for Contra Body Movement Position. It is a position where you place one foot along or across (in this case, along) the path of the other foot, with the opposite side of the body turned toward the moving foot.
The last step of the Progressive Chasse (which is technically the first step of the following figure) is taken in CBMP by both man and lady due to the outside partner position. The CBMP position enables you to sneak outside partner while maintaining body contact. If you were to step straight forward on a separate track as normal, without turning the body -- in this case to the right -- stepping outside partner would require you to shift leftward to make room for your leg, causing you to lose body contact and compromise your frame. Therefore, you will notice that all steps taken in outside partner position are indicated as being taken "in CBMP".