1 NONCOINCIDENT VASI SYSTEMS - These VASI systems have a Glide Slope Angle and/or Runway Point of Intercept which differs from the Precision Approach Radar or the radio navigation precision approach system (Instrument Landing System or Microwave Landing System). Noncoincident VASI systems will be reported in the Enroute Supplement under  "Service".
2 NONSTANDARD VASI SYSTEMS - Nonstandard VASI systems may consist of varying approach light configurations such as T-VASIs or Tri-color VASIs. Although nonstandard, they provide the same visual descent guidance as the two or three light bar VASI systems.
3 LOW COST VASI/LCVASI - This VGSI system consists of three sets of four white lights on three mounts, usually installed on only one side of the runway. LCVASI indicates only above, on, or below the glide path and does not indicate the magnitude of any deviation. See paragraph 5-41.
(b)
PRECISION APPROACH PATH INDICATOR/PAPI - This VGSI system consists of four light boxes, similar to the standard VASI light boxes, installed in a horizontal row on one side of the runway, usually the left side. When on glide path, the pilot will see two red lights and two white lights. When the aircraft deviates from the normal glide path, the combination of red and white lights change. At some locations, light boxes may be installed on both sides of the runway. This does not affect the system operation.

(c)
PULSATING VISUAL APPROACH SLOPE INDICATOR / PVASI - This VGSI system normally consists of a

single light unit projecting a two-color visual approach path. The on glide path indication is a steady white light, the above glide path indication is a pulsating white light, the below glide path indication is a pulsating red light with a slightly below glide path indication of a solid red light. As the deviation above or below the glide path increases, the duration of the pulses (white or red) decreases and reaches zero at the upper edge of the viewing range of the system. The useful range of this system is approximately 4 miles during the day and up to 10 miles at night.
(8)
BOUNDARY LIGHTS - Lights defining the perimeter of an airport or landing area.

(9)
RAPID EXIT TAXIWAY INDICATOR LIGHTS (RETIL) - Consist of a group of yellow lights in a 3-2-1 sequence spaced 328 ft apart to a rapid exit taxiway. The lights are installed on the same side of the runway centerline as the associated rapid exit taxiway.

AIRPORT MARKING AIDS - Markings used on runway and taxiway surfaces to identify a specific runway, a runway threshold, a centerline, a hold line, etc. A runway should be marked in accordance with its present usage such as:
(1)
Visual.

(2)
Non-precision instrument.

(3)
Precision instrument.

AIRPORT REFERENCE POINT - The approximate geometric center of all usable runway surfaces.
AIRPORT ROTATING BEACON (NGA) - A visual navigational aid operated to aid identification of the airport. The rotating beacon flashes one or two colors alternately. Flashes may be produced by an omnidirectional capacitor discharge device or a light source rotating at a constant speed. Beacon colors are: