text: Appendix A
  Figure A-6. Dispersed assembly area method
  Boundaries
  A-16. A boundary is a line that delineates surface areas for the purpose of facilitating coordination and
  deconfliction of operations between adjacent units, formations, or areas (JP 3-0). Boundaries are normally
  drawn along identifiable terrain features and are used to delineate responsibility between adjacent units and
  between higher and lower echelon headquarters. Boundaries should not split responsibilities for key or
  decisive terrain, roads, rivers, or railways. Within their assigned areas, units may maneuver within the overall
  plan without close coordination with neighboring units unless otherwise restricted. Direct fire may be placed
  across boundaries on clearly identified enemy targets without prior coordination, provided friendly forces are
  not endangered. Indirect fire also may be used after prior coordination with the adjacent unit. Commanders
  adjust boundaries as necessary in response to the evolving tactical situation.
  A-17. Boundaries by themselves or with other control can be used to define a unit’s assigned area: area of
  operations, zone, or sector. A forward boundary is a boundary that delineates the forward edge of a unit’s
  area of operation. A lateral boundary is a boundary defining the left or right limit of a unit’s assigned
  area. A rear boundary is a boundary that delineates the rearward limits of a unit’s assigned area. The
  forward boundary is the farthest limit in the direction of the enemy, of an organization’s responsibility. The
  rear boundary also defines the start of the next echelon’s rear area. Figure A-1 on page A-2 depicts an AO
  with forward, rear, and lateral boundaries.