text: Operations During Armed Conflict
  forces. Army forces establish C2 of land areas at the direction of the joint force commander (JFC), normally
  the JFLCC. A JFLCC is the commander within a unified command, subordinate unified command, or joint
  task force (JTF) responsible to the establishing commander for recommending the proper employment of
  assigned, attached, or other available land forces; planning and coordinating land operations; and
  accomplishing assigned missions. C2 across the width and depth of the land component commander’s
  assigned areas requires access to strategic communications. Therefore, commanders plan for the movement
  and placement of strategic communications systems in C2 nodes. (See JP 3-31 and FM 3-94 for more
  information on the JFLCC.)
  6-37. In addition to their assigned missions, Army forces generally consider four key issues. They are the
  assignment of subordinate land areas, the concept of mutual support between subordinates, the integration of
  echelons in terms of time, space, and purpose, and the proper task organization of the land force.
  Assigning Land Areas
  6-38. The JFC typically assigns a land area of operations (AO) to the land component command. A land AO
  does not typically encompass the entire land operational area of the JFC’s joint operations area (JOA), but
  the size, shape, and positioning should be adequate for the JFLCC to accomplish the mission and protect the
  forces under the JFLCC’s control. In the assigned land AO, the JFLCC establishes an operational framework
  for the AO that assigns responsibilities to subordinate ground force commanders and allocates capabilities to
  fulfill those responsibilities. Based on the situation, the land component command assigns areas (AO, zone,
  or sector) to subordinate tactical echelons. Figure 6-1 on page 6-8 reflects a baseline doctrinal template for
  depths and frontages by echelon. (See Chapter 2 for more information on considerations for how to assign
  areas to subordinate echelons.)
  Note. Political constraints, geography, ally and partner dynamics, forces available, the types of
  operations being conducted, and the enemy all influence the appropriate AO size for each echelon.