They served a master with a special skill of family businesses, such as military arts and knowledge of the Ritsuryo codes, (service) and gained benefit, such as a government post, in exchange (favor).
主となった者に武芸や律令知識などの家業とする専門技能で奉仕し（奉公）、代わりに官職等の利益（御恩）を得た。