VGSI is the visual guidance (VASI or PAPI) and RNAV is the electronic guidance on an instrument approach. When the VGSI and RNAV glidepaths are not exactly the same, it is said that they are not coincident.

RNAV is Radio Navigation ("nav"). It is a form of electronic navigation that uses DME and other signals to form a point in the distance that an aircraft can fly to even though there is no actual signal coming from that point.

E. D. McConkey has written:

'RNAV route design' -- subject(s): Navigation (Aeronautics), Air traffic control

Class E airspace at low altitude federal airways are indicated by center line.

Intersection-arrows are directed towards facilities which establish intersection.

Class E airspace at low altitude federal airways are indicated by center line.

Intersection -arrow are directed towards facilities which establish intersection.

Class E low altitude RNAV 2 routes are indicated by center line.