I (移) (移)
"I" (移) is a form of official documents under the ritsuryo system (a system of centralized government based on the ritsuryo code), to be exchanged between government officials when there are no hierarchical relationships between them. However, when either or both of the parties are Ryoge no kan, cho instead of "I" (移) should be used.
In China official documents in a form of i have been used since ancient times, and according to "Bunshinchoryu" (the oldest Chinese literature and rhetoric compendium) "I" (移) means "to change the real world,"because "I" (移) can be represented in a Chinese character which means "change" instead of one which means "move." Stipulations about "I" (移) can be seen in the remaining part of Kaigen Ritsuryo of Tang dynasty which was excavated from the remains in Dunhuang City; they are similar to stipulations about "I" (移) in Kushiki-ryo (law on state documentary forms in the Yoro Code) of Taiho Ritsuryo and Yoro Ritsuryo and so it is believed that "I" (移) in Japan was brought from China code. Every government official is in some form of hierarchical relationship with other officials under Ritsuryo law, and "I" (移) was used to exchange documents between officials who are not in hierarchical relationships with each other.
According to Kushiki-ryo, an "I" document began with a sentence saying "xxx {name of sender] isu yyy [name of recipient]" in the first line, described the main content in and below the second line, and generally finished with a sentence saying "Kotosara-ni isu"; if the sender was legally authorized to give orders and instructions to a recipient with whom he did not have a hierarchical relationship, the last sentence of the main content was "motte isu," making the "I" into an order. After that, the date and the sender's Isho (rank and name in a row) are written, and finally Isho of kyo (minister) of sho (ministry) to which the sender belongs is written. It was stipulated, however, that 寮司 could not send "I" (移) directly to other sho or officials of other sho; instead, 寮司 had to send ge (an official document) in advance to the sho which the receiver belonged to, asking for permission to send "I" (移), and then the sho which 寮司 belonged to sent "I" (移) to the sho which the receiver belonged to.
In 719, as to exchanges of documents between Sogo (a monk of a managerial post)/Sango (three monastic positions with management roles at a temple) and Zokkan government officials, which should use cho, it was stipulated that a form of "I" (移) should be used by replacing Chinese characters "I" (移) with "cho" (牒). Such stipulation was reflected in Kushiki-ryo of Yoro Ritsuryo as well, and regarded as one of the greatest difference from Taiho Ritsuryo. Though formerly government officials exchanged documents in a form of "I" (移) under the ritsuryo system, distinction became vague with an increase in number of Ryoge no kan, who used cho, and officials issued more and more documents in a form of cho instead of "I" (移). "I" (移) was limited to exchange of official documents among government officials, and it is believed that all the documents in a form of "I" (移) were destroyed after the storage period expired. Thus it is believed that no documents in a form of "I" (移) exist today, with the exception of Shoso-in monjo (documents of Shoso-in).