Although a Gonaisho was written in the style of a private letter with the sender's name written in the text, a kao (written seal mark) or shohan (signature/seal) was added to the document by the shogun himself.
形式そのものは差出人が文面に表記される私信と同じものであるが、将軍自身による花押・署判（署名・捺印）が加えられていた。