Zi (辞)
Zi is monjo (written material) used by lower-ranking government officials equal to or below the rank of Zonin or by the common people or hakucho (inferior servants) when they reported to their superiors, under the ritsuryo system (a system of centralized government based on the ritsuryo code).
According to Kushiki-ryo (law on state documentary forms in the Yoro Code) (Ritsuryo law), there was a prescribed format of zi, 'the date, the name of the reporter, the main text and kinji (a closing sentence).'
However, probably because this prescription was difficult to understand, mostly other forms such as ge (a form of an official document) were used in issuing an official document which ought to have been made as zi, and thus zi does not remain today.
But it is believed that zi was actually made, because phrases such as "kinji," which are thought to be influenced by zi, are used in letters of sohaku used for exchange of territories.