text: Appendix B
  headquarters is typically responsible for executing the ADCON responsibilities for subordinate Army units
  under its command unless modified by a higher headquarters.
  Attached
  B-21. Attached units are temporarily subordinated to the gaining headquarters, often for months or longer.
  They return to their parent headquarters (assigned or organic) when the reason for the attachment ends. The
  Army headquarters that receives another Army unit through assignment or attachment assumes responsibility
  for certain ADCON requirements, and particularly sustainment, that normally extend down to that echelon,
  as specified by directives or orders. For example, when an Army division commander attaches an air defense
  battery to a BCT, the brigade commander assumes responsibility for unit training, maintenance, resupply,
  and unit-level reporting for that battalion.
  B-22. Army commanders normally place a unit OPCON or TACON to a gaining headquarters for a given
  mission, lasting perhaps a few days. OPCON lets the gaining commander task-organize and direct forces.
  TACON does not let the gaining commander task-organize the unit. Neither OPCON nor TACON affects
  ADCON responsibilities.
  ARMY SUPPORT RELATIONSHIPS
  B-23. Table B-3 lists Army support relationships. 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. If a unit has an established command relationship with
  a headquarters, a support relationship is unnecessary as the command relationship already grants the gaining
  commander all the authorities required. Commanders assign a support relationship when—
  (cid:122) The support is more effective if a commander with the requisite technical and tactical expertise
  controls the supporting unit, rather than the supported commander.
  (cid:122) The echelon of the supporting unit is the same as or higher than that of the supported unit. For
  example, the supporting unit may be a brigade, and the supported unit may be a battalion. It would
  be inappropriate for the brigade to be subordinated to the battalion, hence the use of an Army
  support relationship.
  (cid:122) The supporting unit supports several units simultaneously. The requirement to set support
  priorities to allocate resources to supported units exists. Assigning support relationships is one
  aspect of command and control (C2).
  B-24. Army support relationships allow supporting commanders to employ their units’ capabilities to achieve
  results required by supported commanders. Support relationships are graduated from an exclusive supported
  and supporting relationship between two units—as in direct support—to a broad level of support extended to
  all units under the control of the higher echelon headquarters—as in general support. Support relationships
  do not alter ADCON. Any transfer of ADCON responsibilities should be specified in the order establishing
  the support relationship.