The general rules governing saluting are based on common sense, good manners, and the customs of the times. For instance, soldiers actively engaged in sports are not required to salute, nor is any man leading a horse, since the sudden motion so near the horse's head might make it restive. There will always be occasions when it is inconvenient, impractical, or illogical to render or require the return of a salute. The intent of the regulation is not that it embarrass or demean the individual, but that it serve as a signal of recognition and greeting between members of the military brotherhood. According to regulations, in all services, the salute is initiated by the junior, and at any convenient distance that insures recognition, the least being about six paces. The form of the salute is the same in the Army, Navy and Air Force, and it is given either from the position of attention or at a walk. It is not given indoors except when reporting to another officer in an official capacity. In the Navy, it is customary for the junior initiating a salute to combine it with "Good morning, Sir," as a means of reinforcing its meaning as a greeting. Where this is done in the other two services, it is usually the result of a local directive expressing the wish of a particular commander. While it is expected that the junior will initiate such a greeting, there is no obligation upon him to do so, nor is there any reason that the senior may not say it first. The Navy and Air Force require that the junior, when engaged in work that brings him in reasonably frequent contact with the same seniors during the course of the working day, salute each senior officer the first time that he is passed during the day, but not subsequently unless a change in circumstances requires it. In the Air Force an enlisted mechanic working on the line would salute the engineering officer and his assistants the first time he recognized them during the day. If he passed one of the same officers later in the day, for example in front of the post exchange, he would salute again. The Army requires that a salute be given and returned each time the junior passes the senior, unless circumstances dictate that it be temporarily suspended by common agreement. The Commanding Officer of a naval vessel is saluted whenever met.