A system used to label each structural members of a building before construction, while being dismantled for repair, or during transfer to another site. It is still in use today. The system allows immediate identification of construction materials and their placement. It keeps errors to an absolute minimum. The various marks include: matching patterns, aimon 合紋; spiral marks that rotate in one direction, mawari banzuke 回番付; a combination of geometric marks that can be matched, kumiawase banzuke 組合番付; and zigzag marks, jikō banzuke 時香番付. Black ink is used for the marks that are placed on splicing joints or surfaces, which are not visible when construction is completed. Such labeling has been discovered on structural members of the 1538 Kaisandō 開山堂 of Gyokuhōin 玉鳳院 at Myōshinji 妙心寺 in Kyoto. The system was commonly used by the end of the 16th century, particularly on the structural members of castles. By the 17th-19th century, the method was commonly used even for erecting farmhouses or merchants' houses. When carpenters drew plans for dwellings or shops, they used Chinese number characters (一, 二, 三・・・ichi, ni, san ・・・) and so on for vertical members and hiragana ひらがな (い, ろ, は・・・ i, ro, ha ・・・) and so on for horizontal members.