Soldiers in a formation (say, a pike division) are arrayed by rank and by file. Commands involve rank and/or file, and a soldier's orientation to others in the group is by rank and file.  So, get to know what they are by clicking each of the two terms to the upper right of the soldierly formation. Sergeant Subtlelus says: Aligning oneself to file and to rank constitutes the essence of soldierly order.  It is the relationship of each soldier to all others in maintaining the line.  Comprehend? - LINE, not a haphazard gaggling like civilians at a Saturday market.