A collection of seal impressions gathered into book form. Collections of Chinese seals from the Zhou and Qin dynasties are called ko inpu 古印譜, kodō inpu 古銅印譜, or kandō inpu 漢銅印譜. Ancient seal imprints collected in Japan are called yamato inpu 大和印譜. In both cases, the imprints were collected for study and for appreciation. In the case where original seals are collected and imprints taken from them, the collections are called genkenbon 原鈐本, or jitsuōhon 実押本. These are the most valuable. In cases where the original seal is not available, other methods are: making an impression from a copy of the original seal, carving another seal from an impression on paper; or photographing the impression and publishing it as is. None of these methods is totally satisfactory, but are of some value. The oldest extant collection of seal impressions, the Senwa inpu 宣和印譜, consists of four scrolls dating back to the Northern Song dynasty and is a valuable source of these ancient metal and stone engravings. Many inpu were published during the Song and Yuan dynasties, but most were lost, and it was not until the middle Ming period that interest in old seal impressions revived. In 1572, Wang Chang published the Shūko inpu 集古印譜, which is the oldest available record of ancient Chinese seals today. In Japan, the oldest collection of seal impressions is the Honchō gain 本朝画印 which is appended to Honchō gashi 本朝画史, written in the 17th century.