In the field-related ryo code, it is specified that a field of approx. five hectares should be supplied to each adult man (teidan), of which approx. four hectares was supplied as kubunden and the remaining approx. one hectare as segyoden (this term was changed to eigyoden later).
唐田令では、成年男子（丁男）に100畝（1項約5ヘクタール）を支給し、うち80畝（約4ヘクタール）を口分田として残りの20畝（約1ヘクタール）を世業田（のち永業田に改称）とした。