In identifying a specific headquarters unit, it is usually referred to by its abbreviation as an HHC.
While a regular line company is formed of three or four platoons, an HHC is made up of the headquarters staff and headquarters support personnel of a battalion, brigade, division, or higher level unit.
As these personnel do not fall inside one of the regular line companies of the battalion, brigade, or division, the HHC is the unit to which they are administratively assigned.
Additionally, the HHC will contain further personnel assigned to support and sustain the mission of the battalion headquarters, including maintenance and motor pool, field mess, and supply, as well as the battalion reconnaissance platoon of infantry scouts and snipers and a Mortar Platoon.
[1] At the brigade and division level, an HHC is similarly constituted of the brigade commander or division commander, his or her staff, and the support elements, but the ranks of the staff and support personnel are typically greater to reflect the greater level of responsibility at higher echelon units.