Plain English Meaning
A short label attached to a route name that tells the pilot what kind of navigation equipment the aircraft must have on board to be allowed to fly that route.
Full Definition
A two-character classification code used in the composition of route and procedure designators that indicates a route is established for navigation by aircraft equipped with specific area navigation (RNAV) capability, where 'NAV' identifies the navigation specification category and 'E2' identifies the particular equipment or performance level required to fly that route.
Context Anchor
Seen when completing or reading an ICAO flight plan, especially the NAV/ entry that lists navigation capability for departure, en route, and operations.