This defines the facility number used in call packets on X.25 links with the INL routing option, specifically to carry hop-count information for network routing. Like cdx6500NMNPCCodexGroupFacility, this value must be consistent across every node in the network for hop-count-based routing, and the loop-prevention it enables via cdx6500NMNPCmaxRoutHops, to function correctly, so an admin adding a node must match this to the existing network's setting. For example, a node with a mismatched hop-count facility value could have its calls' hop counts miscounted by other nodes, potentially letting a routing loop go undetected or causing calls to be prematurely rejected as exceeding the hop limit.