This defines the facility number used to carry Codex-proprietary private facility information, other than Hop Count and DCP, which have their own dedicated facilities, in call packets between version-4.xx Codex nodes. Because this must be identical on every node in the network for those private facilities to be correctly parsed on both ends of a call, an admin adding a new node to an existing network must copy this value from the existing nodes rather than leaving it at a factory default that might differ. For example, a newly commissioned node left at its factory-default facility number while the rest of the network uses a different value would fail to correctly exchange these private facility fields with the rest of the network.