The individual signal heads are connected to the SE8C with 10 conductor ribbon cables.
Depending upon which way you assemble the ribbon cables, Pin 1 can be either the brown colored conductor (called Phase A) or the black colored conductor (called Phase B).
To maintain your sanity it seems easiest to be consistent when choosing either conductor, but there is no "wrong" answer.
In the example below, the ribbon cable is being set up using the brown cable as Pin 1, thus it is being configured as "Phase A"
The table below shows the various connections which result when setting up the ribbon cable, both for Phase A and for Phase B: