In contemporary Sōtō Zen, the position of head seat remains an important and prestigious one at training monasteries. Moreover, service as head seat for one retreat 結制安居, at which one goes through rite of dharma combat 法戰式, remains a formal requirement for attaining the rank of a fully fledged 立身 monk, which in turn is a prerequisite for becoming the abbot (resident priest) 住職 of a temple. The great majority of young men who undergo training at Sōtō monasteries are the sons of resident priests who are expected to succeed their fathers as the abbots of ordinary temples, so they all need to serve as head seat for at least one retreat. Because it is not possible for all of them to do so for a full ninety-day retreat at a training monastery, many serve as head seats at an abbreviated retreat 略結制 instead. Abbreviated retreats may last only a few days, and are often held in conjunction with the installation of a new abbot 晉山式. Also written 上座,第一座, 座元, 禪頭, and 首衆.