cotton field jacket was the standard outer garment for all army personnel, except those that had other specialist clothing (Paratroopers wore the parachutist's coat and trousers, tank crews wore the tanker's jacket, various types of  parkas were worn in cold weather, etc.).
For all soldiers, the standard outerwear was a cotton field jacket, but some special units like paratroopers or tank crews had different clothing. Paratroopers wore specialized parachutist gear, while tank crews donned tanker jackets. Parkas were also used for colder climates.