text: Army Tactics
  * Clearance of fires.
  * Security.
  * Personnel recovery.
  * Airspace management.
  * Minimum-essential stability operations tasks, which are—
   Establish civil security.
   Provide immediate needs (access to food, water, shelter, and medical treatment).
  1-57. Commanders can add, remove, or adjust a subordinate units’ AO responsibilities based on the situation
  and mission variables. However, when assigning an AO, a higher echelon headquarters must inform the
  subordinate unit of any changes to the responsibilities listed above.
  Zone and Sector
  1-58. A zone is an operational area assigned to a unit in the offense that only has rear and lateral boundaries
  (FM 3-0). The non-bounded side of a zone is open towards enemy forces. A higher echelon headquarters
  uses fire support coordination and maneuver control measures such as a limit of advance and a coordinated
  fire line to synchronize its deep operations with those of a subordinate unit. Zones allow higher headquarters
  to adjust deep operations without having to change unit boundaries. This gives greater flexibility to the higher
  headquarters for controlling deep operations, allowing subordinate units to focus on close and rear operations.
  A zone is best for front-line units executing high-tempo offensive operations characterized by direct fire
  contact with the enemy and a fluid forward line of troops (FLOT). Units treat everything behind the forward
  line of troops as an AO with the associated nine responsibilities. Zone can be further subdivided as needed.
  (See appendix A for more information on zones.)
  1-59. A sector is an operational area assigned to a unit in the defense that has rear and lateral boundaries
  with interlocking fires (FM 3-0). The non-bounded side is open towards the enemy. A higher echelon
  headquarters uses fire support coordination and maneuver control measures such as battle positions and
  trigger lines to synchronize subordinate units. Higher headquarters are responsible for synchronizing
  operations forward of the main battle and security areas or coordinated fire line. Units use sectors to
  synchronize and coordinate engagement areas and allow for mutually supporting fields of fire, which do not
  require coordination between adjacent units. Units treat everything behind the forward line of troops as an
  AO with the associated nine responsibilities. Sectors can be further subdivided as needed. (See appendix A
  for more information on sectors.)
  Forms of Contact
  1-60. Contact is an interaction between two forces. There are three possible types of interactions:
  * Both forces are in contact with each other.
  * A friendly force is in contact with an enemy force, while the enemy force is out of contact with
  the friendly force.
  * A friendly force is out of contact with an enemy force; however, the enemy force is in contact with
  the friendly force.
  1-61. The forms of contact describe the method of interaction that positively identifies the location or activity
  of a force. The forms of contact also—
  * Quickly describe to others what is happening.
  * Describe the method of engagement.
  * Provide an understanding of a force’s capabilities and ranges.
  * If a force is in contact, can trigger additional actions, typically in the form of battle drills.
  1-62. An exception to these forms of contact are interactions with friendly or neutral entities such as civilians,
  nongovernmental organizations, or friendly and neutral military forces. This interaction triggers a decision
  from friendly leaders and are usually categorized as a non-hostile form of contact.
  1-63. Whenever a force gains contact with another force, the gaining force can impede the freedom of action
  of that other force while enhancing their own freedom of action. For example, after gaining visual contact on