text: Field Artillery Operations
  FIELD ARTILLERY INHERENT RESPONSIBILITIES IN ARMY
  SUPPORT RELATIONSHIPS
  4-51. In the past, DS, R, GSR, and GS were referred to as FA tactical missions. These tactical missions are
  now referred to as support relationships and are used by the rest of the Army to task-organize forces.
  4-52. Army support relationships are not a command authority and are more specific than the joint support
  relationships. Commanders establish support relationships when subordination of one unit to another is
  inappropriate. Commanders assign support relationships when: the support is more effective if a commander
  with the requisite technical and tactical expertise controls the supporting unit rather than the supported
  commander; the echelon of the supporting unit is the same as or higher than that of the supported unit; or the
  supporting unit supports several units simultaneously (ADP 5-0). Organic FA BNs can be assigned a support
  relationship by the FFA HQ of the supported command.
  4-53. Support relationships allow commanders to employ their units' capabilities to achieve the desired
  results required by supported commanders. Support relationships are graduated from an exclusive supported
  and supporting relationship between two units-as in DS-to a broad level of support extended to all units under
  the control of the higher HQ-as in GS. Support relationships do not normally alter administrative control.
  Support relationships are used to task-organize for a mission. FA units may be assigned a support relationship
  of DS, R, GSR, or GS.
  4-54. The seven FA inherent responsibilities (see table 4-1 on page 4-11) supplement the inherent
  responsibilities of an Army support relationship. For more information on command and support
  relationships see FM 3-0.
  DIRECT SUPPORT
  4-55. Joint doctrine considers direct support a mission rather than a support relationship. For the Army, and
  FA, direct support is a support relationship requiring a force to support another specific force and authorizing
  it to answer directly to the supported force's request for assistance (FM 3-0). A FA unit in DS of a maneuver
  unit is concerned primarily with the fire support needs of only that unit. The FSE of the supported maneuver
  unit plans and coordinates fires to support the maneuver commander's intent.
  4-56. The commander of a unit in DS recommends position areas and coordinates for movement clearances
  where his unit can best support the supported commander's concept of the operation. When FA units are able
  to habitually support the same supported force, coordination and training are enhanced. DS is the most
  decentralized support relationship.
  REINFORCING
  4-57. Reinforcing is a support relationship requiring a force to support another supporting unit (FM 3-0).
  Only like units (for example artillery to artillery) can be given an R support relationship. An R support
  relationship requires one FA unit to augment the fires of another FA unit.
  4-58. When an organic or DS FA BN requires more fires to meet supported force requirements, another FA
  BN may be directed to reinforce it. An organic or DS FA BN may be supported by up to 2 R BNs. A FA unit
  assigned an R support relationship retains its command relationship with its parent unit but is positioned by
  the reinforced FA unit and has priorities of support established by the reinforced FA unit, then the parent
  unit.
  GENERAL SUPPORT-REINFORCING
  4-59. General support-reinforcing is a support relationship assigned to a unit to support the force as a whole
  and to reinforce another similar type unit (FM 3-0). The first priority of a FA unit assigned a GSR support
  relationship is to furnish artillery fires for the supported force as a whole; the second priority is to reinforce
  the fires of another FA unit.