"In American football, a T formation (frequently called the full house formation in modern usage) is a formation used by the offensive team in which three running backs line up in a row about five yards behind the quarterback, forming the shape of a "T".
Numerous variations of the T formation have been developed, including the Power-T, where two tight ends are used, the Pro T, which uses one tight end and one wide receiver, or the Wing T, where one of the running backs (or wingback) lines up one step behind and to the side of the tight end. Any of these can be run using the original spacing, which produced a front of about seven yards, or the Split-T spacing, where the linemen were farther apart and the total length of the line was from 10-16 yards." [T formation. Wikipedia]
The American football positions diagram example "Offensive formation - T-formation" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Football solution from the Sport area of ConceptDraw Solution Park.