roller derby rules explicitly forbid inline skates for players. (USARS requires quad skates for all skaters. WFTDA and MRDA permit inline skates for referees, but virtually all referees wear quad skates.) Individual teams may mandate additional gear, such as padded knee length pants, similar to what aggressive skateboarders wear, and gender specific gear such as a hard-case sports bra for female players and protective cups for males. Strategy and tactics Offense and defense are played simultaneously, a volatile aspect that complicates strategy and tactics. For example, one team's blockers may take offensive action to create a gap in the opposing wall for their jammer to pass through, but this same maneuver could potentially weaken their own defenses and allow the opposing team's jammer to score. Strategies (high-level plans toward achieving the game's goal, which is to outscore the opposition) include the following: Ending the jam: The lead jammer can "call off" or end the jam at any time, controlling the opposition's ability to score points. The strategy for a jam is not to score a lot of points but to outscore the opposition. Often, the lead jammer scores as many points as possible on the first scoring trip, and then ends the jam before the opposing jammer has the opportunity to score any points. If the jammer gets the lead but is then passed by the opposing jammer, they may decide to call off the jam without scoring any points themselves in order to prevent the other team's jammer from scoring any points. Passing the star: The jammer for a team may "pass the star" (may perform a "star pass") to the pivot—that is, hand the helmet cover with the star to the pivot, which turns the pivot into the jammer. Passing the star does not nullify any earned pass of an opponent that the former jammer made, but passing the star forward never constitutes an earned pass. A jammer might pass the star because of fatigue, injury, or because the pivot is in a better position to score. Passing the star is also sometimes referred to as "passing the panty", as helmet covers are sometimes known as "panties". Killing a penalty: Captained by the pivot, blockers adapt their play to a penalty situation. For example, a short-handed team may try to make the pack skate faster to slow down scoring action until the team returns to full strength. Tactics