Officers, battalion noncommissioned staff officers, platoon leaders, guides, and musicians are equipped with whistles.

The major and his staff will use a whistle of distinctive tone; the captain and company musicians a second and distinctive whistle; the platoon leaders and guides a third distinctive whistle.

35.  Prescribed signals are limited to such as are essential as a substitute for the voice under conditions which render the voice inadequate.

Before or during an engagement special signals may be agreed upon to facilitate the solution of such special difficulties as the particular situation is likely to develop, but it must be remembered that simplicity and certainty are indispensable qualities of a signal.

ORDERS.

36.  In these regulations an ORDER embraces instructions or directions given orally or in writing in terms suited to the particular occasion and not prescribed herein.

ORDERS are employed only when the COMMANDS prescribed herein do not sufficiently indicate the will of the commander.

ORDERS are more fully described in paragraphs 378 to 383, inclusive.

COMMANDS.

37.  In these regulations a command is the will of the commander expressed in the phraseology prescribed herein.

38.  There are two kinds of commands: 

The PREPARATORY command, such as forward, indicates the movement that is to be executed.

The command of EXECUTION, such as MARCH, HALT, or ARMS, causes the execution.

Preparatory commands are distinguished by italics, those of execution by CAPITALS.

Where it is not mentioned in the text who gives the commands prescribed, they are to be given by the commander of the unit concerned.

The PREPARATORY command should be given at such an interval of time before the command of EXECUTION as to admit of being properly understood; the command of EXECUTION should be given at the instant the movement is to commence.

The tone of command is animated, distinct, and of a loudness proportioned to the number of men for whom it is intended.

Each PREPARATORY command is enunciated distinctly, with a rising inflection at the end, and in such manner that the command of EXECUTION may he more energetic.

The command of EXECUTION is firm in tone and brief.

39.  Majors and commanders of units larger than a battalion repeat such commands of their superiors as are to be executed by their units, facing their units for that purpose.  The battalion is the largest unit that executes a movement at the command of execution of its commander.

40.  When giving commands to troops it is usually best to face toward them.

Indifference in giving commands must be avoided, as it leads to laxity in execution.  Commands should be given with spirit at all times.