text: Command and Support Relationships
  ARMY COMMAND AND SUPPORT RELATIONSHIPS
  A-19. Army command and support relationships are similar but not identical to joint command relationships.
  Differences stem from the way Army forces task-organize internally and the need for a system of support
  relationships between Army forces. Another important difference is the requirement for Army commanders
  to provide administration and support to subordinate Army forces. These differences allow for flexible
  allocation of Army capabilities within various Army echelons.
  ARMY COMMAND RELATIONSHIPS
  A-20. Army command relationships define superior and subordinate relationships between unit commanders.
  By specifying a chain of command, command relationships unify effort and enable commanders to use
  subordinate forces with maximum flexibility. Army command relationships identify the degree of control of
  the gaining Army commander. The type of command relationship often relates to the expected longevity of
  the relationship between the headquarters involved and quickly identifies the degree of administration and
  support that the gaining and losing Army commanders provide. Army command relationships include—
  * Organic.
  * Assigned.
  * Attached.
  * OPCON. (See paragraphs A-7 and A-8.)
  * TACON. (See paragraph A-9.)
  Organic
  A-21. Forces that are organic are assigned to and forming an essential part of a military organization as listed
  in its table of organization for the Army, Air Force, and Marine Corps, and are assigned to the operating
  forces for the Navy (JP 1). For example, combined arms battalions, field artillery battalion, cavalry squadron,
  brigade engineer battalion, brigade support battalion, and headquarters and headquarters company are all
  organic units to an armored BCT. The Army establishes organic units through organizational documents such
  as tables of organization. Army commanders exercise OPCON and ADCON of organic forces.
  Assigned
  A-22. Assign is to place units or personnel in an organization where such placement is relatively permanent,
  and/or where such organization controls and administers the units or personnel for the primary function, or
  greater portion of the functions, of the unit or personnel (JP 3-0). For example, BCTs, DIVARTY, and a
  sustainment brigade are assigned to a division. Army assigned units remain subordinate to the higher echelon
  headquarters for extended periods, typically years. Assignment is based on the needs of the Army, and it is
  formalized by orders rather than organizational documents. Although force tailoring or task-organizing may
  temporarily detach units, they eventually return to either their headquarters of assignment or their organic
  headquarters. Army commanders exercise OPCON and ADCON of assigned forces.
  Attached
  A-23. Attach is the placement of units or personnel in an organization where such placement is relatively
  temporary (JP 3-0). A unit temporarily placed into an organization is attached. When an Army force is
  attached to another Army headquarters, the attachment order specifies the command relationship of OPCON
  or TACON. The gaining unit exercises ADCON of the attached Army force unless modified.