Fu is an official document used by government officials in the upper grade to give a command to those in the lower grade under the ritsuryo system.
Fu issued by Daijokan (Grand Council of State) was specially called Daijokanpu, but in organizations other than Daijokan such as Hassho and danjodai a command was given to officials in the lower grade in the form of fu, and even officials in the low grade used fu to give a command to their subordinate officials. A long and narrow wood plate bearing a 'gunpu,' a command given by gunji (district managers), was excavated from theHachimanbayashi remains (Nagaoka City, Niigata Prefecture) and the Yamagaki remains (Tanba City, Hyogo Prefecture).
The format of fu is established in Kushiki-ryo (law on state documentary forms in the Yoro Code), and according to the format, the first line of fu begins with the opening sentence 'So-and-so (The senior official's name) gives a command to So-and-so (the subordinate official's name),' the second line contains the order and the closing line read, "Implement upon receipt." A "Daijokanpu", however, had a summary of command inserted between the opening sentence and the second line that contained the actual command. And instead of the closing sentence stipulated in Kushuki-ryo being used ("Implement upon receipt"), informal closing sentences such as "especially commanded" or "hereby commanded" were used. Beneath the closing sentence was written the position, rank and name (in that precise order) of the official who issued the document, and on the line under it was the date it was issued (In the cases of a Daijokanpu, the rank and name of the Benkan (Daijokan official) is written on the upper part, and the name of the scribe is placed under it, as required by the Ritsuryo system). The format of placing the closing sentence, the rank and name of the issuer, and the date of issue on individual lines in that precise order was used solely in "fu" and proved that the document was a "fu". Although some of the other parts were changed and/or omitted, the position and order of the lines that stated the rank of the issuer, and the date of issue, was never changed or omitted.
Below the date of issuance, the rank and name of the messenger who carried the document to the receiver were written, and concluded with, 'Refer to the procedures of the formal fu in cases of reikoku and denfu (relay messenger system, or when a document had been sent via relay messenger to officials in various districts).'
After the mid Heian period, "Daijokan-pu" (the "fu"issued by the Grand Council of State) was replaced by the "Kansenji" (a government edict), while non-Grand Council officials used various forms of "kudashi-fumi" (order papers sent to subordinates) instead of the "fu." Some of the "Fu," such as "Daijokan-pu," were occasionally issued after that, and remained as a official document form until the Meji Restoration ended the Ritsuryo system.