I always assumed this was some kind of "custom patch" facility, so that Mother could supply (encrypted, no doubt) patch files of some sort that would alter some of the fixed (lab) non-user alterable parameters in the codeplug. They came out with firmware and CPS updates so often this probably never was needed in practice. If it was ever used, it probably was to supply a large customer with an emergency patch until the firmware/CPS update came out that would include it.