This read-write setting classifies this interface's role for the routing or AutoRoute layer as a user port, routing trunk, feeder trunk, clock port, or virtual trunk, defaulting to user port, uni-style, and only changeable to a trunk type when there are no active connections on the port. It governs how PAR treats the interface for routing purposes, and the description notes the change is blocked while connections exist, protecting live traffic from a disruptive reclassification. An admin repurposing a customer-facing port into an inter-node trunk must first ensure no connections remain on it before changing parIfType from userport to routingtrunk.