Castle plan; general term for the layout of a castle and its component structures. Lit. "stretched rope," the term is said to derive from the fact that originally a rope was stretched between stakes, positioned at intervals, to determine the placement of the castle compound and components. Before the 17th century, precise drawings were not made; a general plan of a castle and its surroundings were made directly, according to the lay of the land. Fundamental to the plan is the placement of the enclosures *kuruwa 郭, moats *hori 堀, earth and stone ramparts *doi 土居 and sekirui 石塁, entrances *koguchi 虎口 and roads. Castles are classified into single-compound and multi-compound structures. Multiple-compound castles were constructed in a number of different layouts, including concentric circles, concentric squares, plans with compounds aligned along an axis or those with whirlpool layouts or star-shaped plans. They are called *teikakushiki 梯郭式, renketsushiki 連結式, goryōkakushiki 五稜郭式. Plans are also conceived in terms of the basic function of the castles: some are primarily defensive, whilst others are offensive installations. Early modern Japanese military scholars, using the principles of Chinese yin and yang thought, termed defensive castle plans in-no-nawa 陰の縄, and offensive castles plans yō-no-nawa. 陽の縄. Similar terminology was applied to component castle structures.
