text: Appendix J
  Uses of Visual Signals
  J-30. These signals can be used to identify a critical trail junction, mark a rally or rendezvous point,
  mark caches, or report that a danger area is clear. White powder can be used to indicate direction at a
  confusing trail intersection. A flashlight with a blue filter (with an "X" cut out of the filter) can signal "All
  clear" to a unit crossing a danger area. The possibilities are endless. However, the leader ensures that each
  Soldier in the team understands every signal used.
  TOUCH SIGNALS
  J-31. These consist of wire, string, or rope used in the hide or surveillance position to communicate
  without disclosing the position. They usually consist of wire loosely secured to an arm or leg. By
  prearrangement, two pulls on the wire might mean that a ground-mounted force is approaching, while three
  pulls might indicate a convoy.
  TARGET DETECTION
  J-32. Successful night movement and target engagement depend on knowing the enemy--how he
  attacks, defends, and uses terrain. Studying the enemy's techniques and patterns aids in target detection.
  Nature provides an endless array of patterns. Man invariably disturbs or alters these patterns so they are
  detectable. Sensing the enemy at night requires leaders and Soldiers to exercise patience, pay attention to
  detail, and practice. Patience and confidence are critical to effectively sense a target at night. While moving
  through an area, Soldiers look calmly and methodically for patterns rather than on details. For example,
  they look for straight lines, light variations, and any other odd-looking, obviously man-made, or disturbed
  patterns. The team looks for sentries or positions at the entrances to draws, on hills overlooking bridges or
  obstacles, and on the military crests of prominent terrain features. This is where the enemy will go for
  observation. The team also looks for supporting positions. They must know the ranges of enemy weapons,
  including supporting weapons, as well as the ranges of the enemy's night vision and line-of-sight
  observation devices. They must search thoroughly for enemy positions and for any other signs of
  enemy activity. Typical indicators of enemy activity include sounds, odors, displacement, weathering,
  littering, and camouflage:
  Sounds
  J-33. A Soldier places an ear to the ground or drives a stick 6 inches into it. Ground is denser than air,
  so sounds can travel farther through it, although determining direction is difficult. Rain and winds mask
  sounds. Rain causes Soldiers to seek shelter in static positions or, if moving, to put down their earflaps.
  Both actions degrade the ability to hear someone stalking them.
  Odors
  J-34. When the sun sets, the air cools and odors float downhill. When the sun and temperatures rise, so
  do odors. The more odors rise, the more likely they are to be picked up and carried by the wind.
  Displacement
  J-35. The team checks for displaced stones, leaves, or logs. The undersides of these objects are usually
  darker in color than their top sides, and they are usually also damp. Crumbled rocks have lighter colored
  faces and chips. At night, Soldiers need flashlights to detect these signs, so the team must place security
  well out. When viewed through infrared devices, broken and crushed vegetation look very different from
  undisturbed vegetation.
  Weathering
  J-36. Weathering indicates a recent disturbance. At night, the team usually needs experience--and
  light--to detect weathering.