Above the zav [is] a zavah, in that she transmits tumah to any man who cohabits with her. Above the zavah [is] a metzora, in that he transmits tumah via entry [into a covered area]. Above the metzora [is] a bone the size of a barley grain, in that it transmits a tumah of seven [days]. More stringent than all of them [is] a corpse, in that it transmits tumah via an ohel, a means through which all the others do not transmit tumah.