There are two ways that a breaching team can ‘stack up’ on a door – one is with all the members on the same side of the doorway (“stack”). If this is the case, the first man will state his entry type (“Cross!” or “Hook!”), with the following team members doing the opposite of the person in front of him/her. If the entry type is not stated, the second man simply does the opposite of what the entry man does, third man does the opposite of the second man, etc.
When ordering a stack, the lead man will either say "stack left" or "stack right" - the directions are relative to facing the doorway. "Stack left" will result in the entry team being on the left side of the door.
The following is a general description of the duties of the breaching team when stacking. Keep in mind that these duties are very contextual, and the focus should be on fluidity rather than doing things exactly by the book.
One Man: The point man, will before the breach maintain security of the breach and never take his eyes or gun away from it. The One Man will initiate the breach when the rest of the breaching team is ready.
Two Man: Keeps security long before breach. If the room needs to be prepped with frags or stuns, this will be the Two Man’s duty.
Three (+Four & Five if applicable) Man: Keeps security to the side (2-4 o’clock) of the stack. If more than four in the team, Three watches ground floor, Four takes upper floors, Five watches 4 o'clock (side-rear).
Last Man (all team sizes): Takes rear security, watching behind the team. The last man is always in the last man role, regardless of team size e.g. In a Fireteam of five, the Fifth man does the last man role and watches the rear, not the “Five man” role described above.
Above: Example of a single stack left, demonstrating how the 2nd man is the person to deploy grenades if needed, to ensure the point man -always- has eyes on the doorway and trigger finger ready