In order to make the shikiji, kurodo always prepared for the imperial order and because the imperial edict was entirely conveyed verbally and the kuzen was made just as a memorandum (memo), the custom was established using sheets of shukushi (also referred to as sukushi), which was simply made by recycling used paper -- That choice of paper formed a part of the document standards later on.
なお、用紙は職事蔵人がいつ勅旨を受けても対応できるように、またあくまでも勅旨伝達は口頭であり口宣は覚書（メモ）として作成されるという性格により、製造が簡便である中古紙を再生した宿紙を用いるのが例とされ、後に書式の一環として定着するようになった。