Final answer:
The command for 'parade rest' can only be given from the position of 'Attention' in formation, and it signifies a posture of readiness and relaxation.
Step-by-step explanation:
The command parade rest may be given when in formation from only one other position, which is Attention. The positions of 'Rest,' 'At ease,' and 'Right face' do not directly precede the command for 'parade rest.' When a drill instructor or leader gives the command for 'parade rest,' all individuals in the formation must move swiftly from the position of 'Attention' into 'Parade Rest,' which signifies a posture of readiness and respect, while also providing a more relaxed stance than 'Attention.' It is a standard command in many military and cadet drill practices.