Back in the good old days, when I was a coder on CICS/MVS 2.1, I split what was then the Intercommunication book into a Guide and Reference....and look how many books these have now evolved into!
As far as MRO operation is concerned, all you need to worry about is the number of Connections INTO the region (from another one) and the number of Connections TO an other one (from the current one).
These connection numbers apply when contact is first established - once they are going, traffic is both ways on them.
These Primary/Secondary Con Winners/Loosers only apply to LU6.2 connections, whereby the Primary/Secondary are the numbers OUTOF/INTO the region and the Con Winners/Loosers say how many of these numbers are reserved for In/Out usage - the excess being up for grabs as required by activity.
This was first published in March 2003