(b) The purpose of =extended order drill= is to teach the =mechanism= of deployment of the firing, and, in general, of the employment of troops in combat. Such drills are in the nature of disciplinary exercises and should be frequent, thorough, and exact, in order to habituate men to the firm control of their leaders. Extended order drill is executed =at ease=. The company is the largest unit which executes extended order drill. (c) =Field exercises= are for instruction in the duties incident to campaign. Assumed situations are employed. Each exercise should conclude with a discussion, on the ground, of the exercise and principles involved. (d) The =combat exercise, a form of field exercise= of the company, battalion, and larger units, consists of the =application of tactical principles= to assumed situations, employing in the execution the appropriate formations and movements of close and extended order. Combat exercises must simulate, as far as possible, the battle conditions assumed. In order to familiarize both officers and men with such conditions, companies and battalions will frequently be consolidated to provide war-strength organizations. Officers and noncommissioned officers not required to complete the full quota of the units participating are assigned as observers or umpires. The firing line can rarely be controlled by the voice alone; thorough training to insure the proper use of prescribed signals is necessary. The exercise should be followed by a brief drill at attention in order to restore smartness and control. (6) =56. Imaginary, outlined and represented enemy.= In field exercises the enemy is said to be =imaginary= when his position and force are merely assumed; =outlined= when his position and force are indicated by a few men; =represented= when a body of troops acts as such. (7) General Rules for Drills and Formations =57. Arrangement of elements of preparatory command.= When the =preparatory= command consists of more than one part, its elements are arranged as follows: (1) For movements to be executed successively by the subdivisions or elements of an organization: (a) Description of the movement; (b) how executed, or on what element executed. (For example: =1. Column of Companies, first company, squads right. 2. March.=--Author.) (2) For movements to be executed simultaneously by the subdivisions of an organization: (a) The designation of the subdivisions; (b) The movement to be executed. (For example: =1. Squads right. 2. March.=--Author.) (8) =58. Movements executed toward either flank explained toward but one flank.= Movements that may be executed toward either flank are explained as toward but one flank, it being necessary to substitute the word "left" for "right," and the reverse, to have the explanation of the corresponding movement toward the other flank. The commands are given for the execution of the movements toward either flank. The substitute word of the command is placed within parentheses. (9)