In the canonical I Ching, the hexagrams are arranged in an order dubbed the King Wen sequence after King Wen of Zhou, who founded the Zhou dynasty and supposedly reformed the method of interpretation. The sequence generally pairs hexagrams with their upside-down equivalents, although in eight cases hexagrams are paired with their inversion.Another order, found at Mawangdui in 1973, arranges the hexagrams into eight groups sharing the same upper trigram. But the oldest known manuscript, found in 1987 and now held by the Shanghai Library, was almost certainly arranged in the King Wen sequence, and it has even been proposed that a pottery paddle from the Western Zhou period contains four hexagrams in the King Wen sequence.Whichever of these arrangements is older, it is not evident that the order of the hexagrams was of interest to the original authors of the Zhou yi. The assignment of numbers, binary or decimal, to specific hexagrams is a modern invention.