text: Countermobility
  necessary guidance on the overall effect of obstacles within a belt. Commanders plan obstacle belts within
  assigned obstacle zones to grant obstacle emplacement authority to their major subordinate units. Obstacle
  belts also focus obstacles to support the brigade scheme of maneuver and ensure that obstacles do not interfere
  with the maneuver of any higher headquarters.
  17-61. Obstacle belts are restrictive. Commanders can direct a subordinate unit to construct one or more
  obstacles to create an effect in an area. They do not specify the type or number of obstacles. Obstacle belts
  do not cross unit boundaries for the same reasons discussed in obstacle zones. (See discussion beginning in
  paragraph 17-57 for more information). A single unit is responsible for a belt; however, a commander may
  assign more than one belt to a unit.
  17-62. A brigade combat team commander normally assigns an obstacle effect and priority to each obstacle
  belt. As with the obstacle zone, the target and relative location are apparent. Adding a specific obstacle effect
  gives purpose and direction to subordinate battalion obstacle planning. When brigade combat team
  commanders assign an obstacle effect, they ensure that obstacles within the belt complement the brigade
  combat team fire plan.
  17-63. A corps, division, or brigade commander may authorize emplacement certain types of protective
  obstacles outside obstacle zones or belts. Normally, the commander authorizes company team and base
  commanders to emplace protective obstacles within 500 meters (546 yards) of their positions, depending on
  the mission variables. The commander usually limits the types of obstacles a unit may use for protective
  obstacles that are outside obstacle control measures. For example, the commander may allow only wire- and
  command-detonated mines outside of control measures for protective obstacles. Furthermore, commanders
  may require that minefields be fenced on all sides, after obtaining legal guidance concerning current rules
  and policies on mine emplacement, to prevent friendly fire incidents.
  Obstacle Groups
  17-64. Obstacle groups are one or more individual obstacles that provide a specific obstacle effect.
  Battalions use obstacle groups to ensure that company teams emplace individual obstacles supporting their
  maneuver schemes. In rare cases, brigades, divisions, or even corps may use obstacle groups for specific
  tactical obstacles. Units integrate obstacle groups with their direct and indirect fire plans. Brigade and
  maneuver battalion commanders plan their placement within designated obstacle zones or belts, respectively.
  17-65. Unlike obstacle zones or belts, obstacle groups are not areas but relative locations for actual
  obstacles. Commanders normally show obstacle groups using the obstacle effect symbols. When detailed
  planning is possible (including detailed ground reconnaissance), commanders may show obstacle groups
  using individual obstacle symbols.
  17-66. Company team commanders and engineers can adjust obstacles in the group if the intent and link to
  the fire plan remain intact. They make minor changes to obstacles and fire control measures based on terrain
  realities. For example, a commander may move a fixing obstacle group and direct fire TRPs 100 meters (109
  yards) to avoid having them masked by rolling terrain. However, a major change to the obstacle group
  location requires the approval of the commander who ordered the obstacle group emplacement.
  Individual Obstacles
  17-67. Each type of individual obstacle, such as abatis and antitank ditches, has its associated symbol. Once
  a unit constructs an individual obstacle, it records the obstacle’s location and reports its emplacement through
  the chain of command. Commanders must report individual obstacles in sufficient detail so that any unit
  moving through the area can bypass or reduce the obstacle without excessive risk. Each headquarters is
  responsible to ensure the dissemination of exact obstacle locations throughout its organization. Commanders
  rarely depict individual obstacle symbols on maps above the battalion echelon. This publication does not
  depict individual obstacle symbols. TM 3-34.85/MCRP 3-17A discusses individual obstacles.
  Obstacle Restrictions
  17-68. Commanders may use obstacle restrictions to provide additional obstacle control and to limit the
  specific types of obstacles used, such as restricting the use of buried mines. These restrictions ensure that
  subordinates do not use obstacles with characteristics that impair future operations. These restrictions also
  allow commanders to focus the use of limited resources for the main effort by restricting their use elsewhere.