Standard Operating Procedure (SOP) is term used frequently in the military. An SOP breaks down any task or group of tasks into simple, lowest common denominator terms. The purpose of this is two-fold:
1)Provide a standardized way of doing things. To inform those of you who have never been through a Military Basic Training or Boot Camp or the like, the military attempts to ingrain conformism and frowns upon individuality. Ideally in the military everything is uniform.
2)Spell out how to do complex tasks like keeping your room clean so that anyone may understand it. An SOP for a barracks room might include the phrases "mirrors will be cleaned daily" or "dirty laundry will not exceed the halfway point of a laundry bag". This is helpful for those of us who would die from inhaling the fumes of our own excrement if we were merely told the ambiguous "Keep your room clean". There may also be pictures.
SOPs exist for almost anything in the military, but most notably:
- living standards
- job specific tasks
- driving
- going to the bathroom (I'd bet money there is one, though I have yet to see it)
SOPs may be written by anyone - I was asked to revise one as a lowly PFC. They are enforced by your chain of command, at many levels. | 
