Nine-fold seal script

Nine-fold seal script (simplified Chinese: 九叠篆; traditional Chinese: 九疊篆; pinyin: jiǔ dié zhuàn) or nine-fold script (simplified Chinese: 九叠文; traditional Chinese: 九疊文; pinyin: jiǔ dié wén) is a highly stylised form of Chinese calligraphy derived from small seal script, using rectilinear, highly recurve, convoluted strokes resembling a space-filling curve. It was used for Chinese characters on seals by the Song dynasty, and for both Chinese characters and Khitan Large characters by the Liao dynasty.

Strokes are conformed to the horizontal and vertical directions. As the name suggests, the strokes of a character are "folded" or "stacked" back on themselves. Depending on the complexity of the character and space constraints of the seal face, however, the number of "fold" rows did not always equal nine, but varied between six and ten.