This read-create INTEGER designates whether the LAPD stack on this row operates as network(1) or user(2), and per the description it can only be set at row creation and cannot be changed afterward. An admin must get this right during provisioning because LAPD's network and user sides behave asymmetrically (for example in link establishment responsibility), so mismatched settings on the two ends of a trunk will prevent the link from coming up. Since it's locked after creation, an admin who provisioned the wrong side would need to delete and recreate the row rather than modify it in place.