According to the Daiho laws one family constituted a household. But the number of a family was not limited: it included brothers and their wives and children, as well as male and female servants, so that it might comprise as many as one hundred persons. The eldest legitimate son was the head of the household, and its representative in the eyes of the law. A very minute census was kept. Children up to three years of age were classed as "yellow" (kwo); those between three and sixteen, as "little" (sho); those members of the household between sixteen and twenty, as "middling" (chu); those between twenty and sixty, as "able-bodied" (tei), and those above sixty as "old" or "invalids," so as to secure their exemption from forced labour (kayaku or buyaku). The census was revised every six years, two copies of the revised document being sent to the privy council (Daijo-kwan) and one kept in the district concerned. It was customary, however, to preserve permanently the census of every thirtieth year* for purposes of record, and moreover the census taken in the ninth year of Tenchi's reign (670)** was also kept as a reference for personal names. To facilitate the preservation of good order and morality, each group of five households was formed into an "association of five" (goho or gonin-gumi) with a recognized head (hocho); and fifty households constituted a village (sato or mura), which was the smallest administrative unit. The village had a mayor (richo), whose functions were to keep a record of the number of persons in each household; to encourage diligence in agriculture and sericulture; to reprove, and, if necessary, to report all evil conduct, and to stimulate the discharge of public service. Thus the district chief (guncho or gunryo) had practically little to do beyond superintending the richo. *This was called gohi-seki; i.e., comparative record for a period of five times six years. **It was designated the Kogoanen-seki, from the cyclical name of the year. THE LAND The land laws of the Daiho era, like those of the Daika, were based on the hypothesis that all land throughout the country was the property of the Crown, and that upon the latter devolved the responsibility of equitable distribution among the people. Rice being the chief staple of diet and also the standard of exchange, rice-lands--that is to say, irrigated fields--were regarded as most important. The law--already referred to in connexion with the Daika era but here cited again for the sake of clearness--enacted that all persons, on attaining the age of five, became entitled to two tan of such land, females receiving two-thirds of that amount. Land thus allotted was called kubun-den, or "sustenance land" (literally, "mouth-share land"). The tan was taken for unit, because it represented 360 bu (or ho), and as the rice produced on one bu constituted one day's ration for an adult male, a tan yielded enough for one year (the year being 360 days).*