text: Operational Art and Science
  normally the JSA; however, the field army may expand its rear area beyond the JSA as it shifts the rear
  boundaries of its subordinate corps.
  Support Area
  2-80. Commanders designate support areas within the rear area. A support area is the portion of the
  commander’s AO that is designated to facilitate the positioning, employment, and protection of base
  sustainment assets required to sustain, enable, and control operations (ADP 3-0). It is where most of the
  echelon’s sustainment capabilities originate from and includes lines of communication, bases, and base
  clusters. The support area is generally the AO assigned to a maneuver enhancement brigade (MEB). The
  MEB is responsible for terrain management, movement control, mobility support, clearance of fires, and
  tactical combat forces for security. This allows sustainment units to focus on their primary function. Field
  armies, corps, and divisions may have one or multiple support areas, located as required to best support the
  force.
  Decisive, Shaping, and Sustaining
  2-81. This decisive, shaping, and sustaining framework lends itself to a broad conceptual orientation of the
  operation. When used in conjunction with the other frameworks, it provides greater understanding of the
  purpose that the formation is trying to accomplish. The decisive operation is the operation that directly
  accomplishes the mission (ADP 3-0). It is the focal point around which commanders design their entire
  operation. The commander conducts decisive operations by—
  * Task-organizing for the decisive operation.
  * Allocating resources by establishing priorities of support.
  * Echeloning combat power.
  * Assigning appropriate areas of operations.
  * Employing other forces to shape conditions to guarantee success of the decisive operation.
  2-82. Commanders identify a single decisive operation and arrange all other operations around that
  operation. A decisive operation may include multiple subordinate units to ensure its success. This is
  especially true at higher echelons where the size and scale of enemy forces may make it impossible for a
  single unit to complete the decisive operation. No echelon will have more than one decisive operation unless
  its mission changes or conditions in an OE change to such a degree that it requires a reconsideration of
  objectives. Commanders will assign the preponderance of their combat power to the decisive operation, while
  shaping operations receive the minimum combat power necessary for their operations. Weighting the decisive
  operation requires the commander to accept risk to guarantee the success of the decisive operation. If shaping
  and decisive operations require more combat power than can be provided simultaneously, the commander
  phases the operation to allow combat power to transfer from shaping operations to the decisive operations
  when the decisive operations begin.