 Occasionally, infringements are not caught by the referee during the match and these may be "cited" by the citing commissioner after the match and have punishments (usually suspension for a number of weeks) imposed on the infringing player.During the match, players may be replaced (for injury) or substituted (for tactical reasons).A player who has been replaced may not rejoin play unless he was temporarily replaced to have bleeding controlled; a player who has been substituted may return temporarily, to replace a player who has a blood injury or has suffered a concussion, or permanently, if he is replacing a front-row forward.