The Operational Service Volume is that volume of airspace surrounding a NAVAID which is available for operational use and within which a signal of usable strength exists and where that signal is not operationally limited by co-channel interference. Operational Service Volume includes all of the following:
(1) The officially designated Standard Service Volume excluding any portion of the Standard Service Volume which has been restricted.
(2) The Expanded Service Volume.
(3) Within the United States, any published instrument flight procedure (victor or jet airway, SID, STAR, SIAP, or instrument departure
(4) Outside the United States, any designated signal coverage or published instrument flight procedure equivalent to U.S. standards.