MCO 3093.4 governs the assignment, management, and operational use of Variable Message Format Unit Reference Numbers.
View MCO 3093.4 on armypubs.army.mil
It establishes Marine Corps policy for Unit Reference Numbers in tactical C4 and ISR systems and defines the Marine Corps management structure. It addresses permanent and spare assignments, the Marine Corps URN Repository, dissemination procedures, and requirements for uniquely assigned URNs.
Applies to: This Order provides the policy for URN assignment and management by units using VMF messages in tactical Command, Control, Communications, and Computer (C4) and Intelligence, Surveillance, and Reconnaissance (ISR) systems.
Per reference (a), the URN is a reference number used by units in a VMF interface to uniquely identify friendly military units, broadcast networks, and multicast groups. (paragraph 2)
A single URN shall exclusively identify an entity. (paragraph 2)
Use of "generic" or "default" URNs is prohibited. (paragraph 4)
System administrators and others with responsibility for initialization of C4 and/or ISR systems shall ensure devices are initialized with appropriately assigned URNs. (paragraph 4)
Each Marine Corps unit shall manage assignment of spare URNs subject to guidance from Marine Expeditionary Force" (MEF) commanders. (paragraph 3)