This is an incomplete list of U.S. Department of Defense code names primarily the two-word series variety. Officially, Arkin (2005) says that there are three types of code name: * Nicknames – a combination of two separate unassociated and unclassified words (e.g. Polo and Step) assigned to represent a specific program, special access program, exercise, or activity. * Code words – a single classified word (e.g. BYEMAN) which identifies a specific special access program or portion. A list of several such code words can be seen at Byeman Control System. * Exercise terms – a combination of two words, normally unclassified, used exclusively to designate an exercise or test