This United States Army manual, Army Regulation AR 750-1 Army Materiel Maintenance Policy February 2023, establishes policies and assigns responsibilities for the maintenance of Army materiel. It provides and defines requirements for performance and management of the materiel maintenance function. It relates to two levels of maintenance: field and sustainment. Field consists of maintenance functions formerly known as operator and/or crew (equipment operators and vehicle crews), unit, and direct support. Sustainment consists of maintenance functions formerly known as general support and depot operations of the Army maintenance system, which is an Armywide program for commodity-unique maintenance. The authorities for this regulation are DoDD 4151.18, DoDI 4151.22, and DoDM 4151.22. This regulation applies to the Regular Army, the Army National Guard/Army National Guard of the United States, and the U.S. Army Reserve, unless otherwise stated. This regulation also applies to the maintenance of all materiel owned or supported by the Army.