It's the 23rd pair of the cable for the ...
In the EL cabinets, as you have discovered already, amphenol cables cover 2 slots in Even/Odd pairs, Slots 2&1, Slots 4&3, Slots 6&5, and Slots 8&7. The first 12 pair are for the second slot and the 13th pair (BK/GR) is skipped and the first card starts at the 14th pair. If these are ONS or DNIC cards it is consecutive, pairs 1-12 are ports 1-12 on the even slot and pairs 14-25 are the odd slot. With 6-port COV or LS/GS Trunk cards it skips every other pair (Port 1 is pair 1, port 2 is pair 3, port 3 is pair 5, etc) and with Universal cards it's a bit different.
The cabling chartscan be found in the SX-200 EL or ICP Technician's Handbook, which can be found pretty easily online.