 It met the initial requirements for a lunar orbit rendezvous and lunar landing mission.It would have consisted of three stages; an S-IB-4 first stage, a S-II-4 second stage and a S-IVB third stage.The first and second stages were essentially four-engine variants of the stages that would be used on the Saturn V, while the IVB stage was actually used on both the Saturn V and the Saturn IB.