text: Chapter 6
  Figure 6-16. Code letters.
  Night Operations
  6-124. For night operations (Figure 6-17), mark the point of impact with—
  y A code letter (made of at least nine lights) placed at the point of impact.
  y One flanker light placed 250 meters to the left and right of the point of impact. If terrain
  restricts the light placement to less than 250 meters, the aircrew will be briefed.
  y A trailing edge amber light placed 1,000 meters, centerline, from the shape designator at the PI
  or at the trailing edge of the surveyed DZ, whichever is closer to the PI (optional). Usually, an
  amber rotating beacon is used.