Zi Collection, Upper Volume, Page 10, Entry 03 "Pronounced xu (rising tone)" — Guangyun "Pronounced yu (rising tone)" — Jiyun Refers to a wild sheep of the plains. Its skin can be used to cover drums, and when struck, the sound of the drum becomes increasingly rapid. Sometimes also written as. Zi Collection, Upper Volume, Page 10, Entry 04 "Pronounced yu (rising tone)" — Jiyun Refers to a wild sheep.