Zi Collection, Upper Volume Radical: Door (hù) Pronounced hu (falling tone) Pronounced gu (falling tone) Meaning: Refers to an edge or corner. Zi Collection, Upper Volume Radical: Door (hù) Pronounced hu (falling tone) Pronounced gu (falling tone) Meaning: Refers to splitting open a bamboo tube to make utensils. Also, "Zhan" is the same as "lu" — "Bo Ya (Boya)". Some say it refers to a bamboo slip, used by children for writing. Others say it refers to a square shape. Zi Collection, Upper Volume Radical: Door (hù) Pronounced gu (falling tone) Also written as "gu" (觚). "Someone picks up a gu and writes freely" — Lu Shiheng, "Wen Fu (Wenfu)". Commentary: A square gu, used by ancients for writing, like modern bamboo slips. Some say gu was made of wood.