Dress Right, Dress
If you are in the military. a cadet program or even a firefighter, law enforcement or EMS, you’ve heard “Dress Right, DXRESS!” at least once.
While you may be amazed with my drawing abilities, stay focused on the info!
Each service, spells out in some detail what is supposed to happen when given the command, Dress Right, Dress. The Air Force specifically states that if an arm is too long, put the hand behind the person to the left.
(Army Training Circular 3-21.5) “On the command of execution [DRESS RIGHT,] DRESS, the first squad leader stands fast and serves as the base. Other squad leaders obtain correct distance by estimation [this means by eyesight, do not put your arm up- do that in training to get the distance. DM]. The members of the first squad execute in the same manner as in squad drill to obtain exact interval. All other squads execute as the first squad, except that each squad member raises the left arm only for uniformity, actually covering (glancing out the corner of the left eye) on the man to the front.”
(Marine Corps Order P5060.20 also for Navy and C0ast Guard)  Says the same thing, more or less. The only difference is that members of the formation meet the fingertips of the individual to their right and the follow up command after, “Ready, Front!” is, “Cover!”. On this command everyone moves directly behind the person in front of them.
(Air Force Manual 36-2203) “As the remaining members align themselves behind the individual in front of or to the right of them, their shoulders may or may not touch the fingertips of the individual to their right. If the arm is too long, place the extended hand behind the shoulder of the individual to the left. If the arm is too short, leave it extended toward the individual to the left and parallel to the ground.”
Dress Left, Dress
Dressing Left is the same procedures as dressing right, but the head turns to the left.
Dress Center, Dress
For regulation drill, dressing left is the same procedures as dressing right, but the head turns to the center.
For ceremonial drill, units dress to the center in different formations, cordons, and colors and this is to stand on marks or to align a certain direction already established.
One instance where dressing to the center is very necessary is the last part of the JROTC Regulation Drill sequence where the team is marching behind the commander toward the head judge. The team should align like this: