CBMP is part of foot position descriptions, so if you're familiar with foot positions, you should already know whether a step is taken in CBMP or not. Of course in the case of the Fleckerls, it's easy to remember... none of the steps are taken in CBMP.
CBM occurs on count 1 and 4 for whomever is moving forward. The man and lady alternate, since when one is rotating in a forwardly direction the other is rotating to the side and back. Therefore when one of them has CBM the other does not. In terms of actual step numbers, the breakdown is thus:
Reverse: Man on 1, Lady on 4
Natural: Man on 4, Lady on 1
There is no rise & fall and no sway.
Regards,
Jonathan Atkinson
www.ballroomdancers.com