According to the relevant information of the query, IO is the abbreviation of IncomingOrder, which means that the English abbreviation "IO" of AOETC is often used as the abbreviation of IncomingOrder. In commodity options, option io refers to the Shanghai and Shenzhen 300 stock index options. The code of the CSI 300 stock index option contract consists of the strike price of the contract type with the letter expiration time.