Meanwhile, the distinction between fullback and halfback was erased, each replaced by "running back" (RB). That term became popular during the 1960s as well, although even into the 1970s, some playing the pro set kept the HB-FB distinction. So, for instance, in the flank formation shown above, those positions were named as in the straight T, while in the "split" version of the deuce backfield, the fullback occupied the other halfback position shown in the straight T. The distinction referred to the build of the players, the fullback being a stronger runner more or less straight ahead, and the halfback faster to attack the defense's flanks. However, on many teams there was no strong distinction between those backs, and since their major role was running with the ball, "running back" was most descriptive without maintaining a spurious geometric connotation that'd become outmoded by their lining up in different depth relationships.