The squad file comprises the whole squad as one single column line, with one Fireteam at the front, the squad leader element in the middle, and the other Fireteam at the rear.
Just like the fireteam column, the squad file is usually used when there is a risk of mines/IEDs or other UXOs, to minimize risk of detonation by ensuring each person steps exactly where the point man did. It can also be used to maintain stealth, as the point man only needs to find a single path for the entire squad, and can easily stop the formation to avoid detection.
Strengths:
- Easiest formation to control, especially on difficult or restrictive terrain
- Allows largest possible volume of fire on both sides
- Easy to maintain at higher movement speeds
- Ideal for maintaining stealth
Weaknesses:
- Vulnerable to the front and rear
- Allows very limited volume of fire forward
- Poor dispersion of troops, especially with limited visibility
- Difficult to transition into base of fire, bounding overwatch, or flanking maneuvers

Above: A squad file, led by the first fireteam leader