type t = {mutable symbol_id : Dtcprotocol_piqi.uint32 option;mutable session_settlement_price : Dtcprotocol_piqi.float64 option;mutable session_open_price : Dtcprotocol_piqi.float64 option;mutable session_high_price : Dtcprotocol_piqi.float64 option;mutable session_low_price : Dtcprotocol_piqi.float64 option;mutable session_volume : Dtcprotocol_piqi.float64 option;mutable session_num_trades : Dtcprotocol_piqi.uint32 option;mutable open_interest : Dtcprotocol_piqi.uint32 option;mutable bid_price : Dtcprotocol_piqi.float64 option;mutable ask_price : Dtcprotocol_piqi.float64 option;mutable ask_quantity : Dtcprotocol_piqi.float64 option;mutable bid_quantity : Dtcprotocol_piqi.float64 option;mutable last_trade_price : Dtcprotocol_piqi.float64 option;mutable last_trade_volume : Dtcprotocol_piqi.float64 option;mutable last_trade_date_time : Dtcprotocol_piqi.float64 option;mutable bid_ask_date_time : Dtcprotocol_piqi.float64 option;mutable session_settlement_date_time : Dtcprotocol_piqi.uint32 option;mutable trading_session_date : Dtcprotocol_piqi.uint32 option;mutable trading_status : Dtcprotocol_piqi.trading_status_enum option;mutable market_depth_update_date_time : Dtcprotocol_piqi.float64 option;}