Most buildings have multiple rooms, and those rooms can have many doors or openings into other rooms.
In this example the operators start with a basic 2-man entry into the first room.
As the number two man begins to “run his wall” he starts to systematically “slice the pie” into the adjacent room. He sees that the far corner is clear and notices a closed door. He may then hand signal his partner that he observes this door.
There are various ways that the operators can approach this door-less opening. The number one man could cross over to the opposite corner and run the wall to stack behind the number two for entry into the next room, and this may be the preferable method for consistency sake; or if there was a door. Otherwise, he could run his own wall to set-up on the opposite side of the doorway. Doing this allows the operators to clear most of the next room except for the immediate corners.
Since there is no door to deal with, another method of entry that can be used here is known as the “criss-cross”.
The criss-cross is a fast yet risky entry method. You both need to be well trained as the chance of bumping into or tripping each other is higher than it is in “stacked” methods of room entry. It’s important that the operators signal who will be moving first as the most common screw-up here is both trying to get through the “fatal funnel” at the same time.
Once the corners are clear and you have reached your points of domination you will then have to set-up on the closed door.
Except this time, instead of moving down the wall, the operator furthest from the door will move across the room to stack behind the point man so that they can make entry on the closed door from the proper side.
Of course all of this precludes having to clear around objects like furniture, closets and other things that may actually be IN these rooms. Keep in mind that these are tactical basics. Real life requires flexibility within your framework of fundamentals.