=Column.=--A formation in which the elements of a command are placed one behind the other. The elements here referred to may be troopers, twos, fours, sections, platoons, or larger units. When used in these regulations as a =word of command=, without qualifying words indicating the kind of column (as =of twos=, =of platoons=, etc.), =column= signifies =a column of fours=. In all other cases the word is to be understood in its general sense unless the context indicates the contrary. =Deployment.=--An evolution in which the command extends its front, as in forming line from column or in passing from close order to extended order. =Depth.=--The space from front to rear of any formation, including the front and rear elements. =Directing leader.=--The leader of a subordinate unit who temporarily conducts the march when the commander is not leading in person. A trooper in the rank of a platoon or smaller unit who similarly conducts the march is termed =a directing guide=. =Direction of march.=--The direction in which the base of the command in question, whether actually in march or halted, is facing at the instant considered. =Disposition.=--The distribution of the elements of a command, and the formations and duties assigned to each for the accomplishment of a common purpose. =Distance.=--The space between men or bodies of troops measured in the direction of depth. Distance is measured--mounted, from the croup of the horse in front to the head of the horse in rear; dismounted, from the back of the trooper in front to the breast of the trooper in rear. =Dress.=--The act of taking a correct alignment. =Drill.=--The exercises and evolutions, taught on the drill ground and executed in accordance with definitely prescribed methods. =Echelon.=--A body of troops is in _echelon_ with reference to another when it is more advanced or less advanced and unmasks or uncovers the other body, wholly or in part; units thus placed are called _echelons_. =Element.=--One of the component subdivisions of a command. As used in these regulations the term _element_ is a general one and may mean a single trooper, a set of twos, a four, section, platoon, or larger unit, according to the command and formation that are being considered. The expression =elements of the column= refers to the several troopers, fours, platoons, or other units that are placed successively, one behind another, in any column formation. =Evolutions.=--Movements by which a command changes its position or passes from one formation to another. =File closers.=--Officers or noncommissioned officers placed out of ranks, whose duty it is to supervise the men in ranks and see that the orders of the commander are carried out. For convenience, this term is applied to any man posted as a file closer. =Flank.=--The right or left of a command in line or column. In speaking of the enemy the term right flank or left flank is used to designate the flank that would be so designated by him.