[a 1] The chiwei were shaped like wings, associated with the Zhuque, also a commonly used as a roof ornamental motif during the Han dynasty.
[a 2] In the Song dynasty, chiwen fully replaced the chiwei and adopted a more dragon-like appearance while also retaining some of their predecessor's bird-like features such as wings or bird's head.
The technical treastise Yingzao Fashi details the proper elements and terminology of the chiwen and formalises their construction and measurements.
[a 3] By the Ming and Qing dynasties, the chiwen was widely used in traditional architecture, their bodies and tail turning more inwards and became very ornate in appearance, with many variations based on regional styles and colors.
A paragraph in the Tang dynasty book Su Shi Yan Yi (蘇氏演義) by Su E (蘇鶚) says that a mythical sea creature called the chi wen [sic] was put on the roofs of buildings during the Han dynasty to protect the structures from fire hazards.
In Japanese mythology, the Shachihoko 鯱 (a mythical fish with a carp's arched tail, tiger's head, and dragon's scales) roof decoration is believed to cause rain and protect against fire.