AIM: The Automated Improvement Mechanism (AIM), is an automated process for crossing orders of any origin type, which provides potential for price improvement and a participation right through an auction process. By utilizing the AIM crossing mechanism, an order flow provider is afforded the opportunity to participate against their customers' orders (facilitation) or solicit another firm's liquidity (solicitation).

AIM AON: AIM for solicited orders of 500 contracts or more. The originator will cross 100% unless responder(s) to the auction price improve the entire quantity.

Caller ID: Order flow providers may choose to identify their executing firm number, correspondent and/or CMTA on HAL, SAL and COA messages.

Cboe Hybrid: Cboe's Hybrid Trading System is designed to provide customers the best of both the electronic and open outcry worlds. With Cboe Hybrid, the speed and efficiencies of a screen-based trading environment are melded with the liquidity and price-discovery of a floor-based, open outcry marketplace.

Cboe Direct: Cboe's state-of-the-art trade engine. Cboe Direct is the platform for Cboe Hybrid, C2, and the Cboe Futures Exchange (CFE).

CFLEX: CFLEX, offered exclusively by Cboe, is an internet-based system for trading FLEX Options (FLexible EXchange options). CFLEX retains the existing advantages of exchange-traded FLEX options while providing a substantial improvement in operational efficiency.

COA: COA (Complex Order Auction) automates the order handling and execution process for certain complex orders while continuing to provide the potential for price improvement through an automated auction process. With COA, eligible marketable and near-marketable complex orders will initiate an auction for price improvement. At the expiration of the auction period, the order will either trade or be booked to the Complex Order Book (COB).

COB: While certain marketable complex orders can be executed automatically in Cboe Hybrid, non-marketable complex orders may be booked in the Complex Order Book (COB). Once introduced in the COB, the resting order will automatically execute if the quotes of the individual legs line up or an opposing order is booked that touches the resting order, or a Cboe quoter submits a strategy quote or order that touches the resting order.

HAL: The Hybrid Agency Liaison mechanism (HAL) automates the handling of NBBO rejects (orders received when Cboe is not on the NBBO). With HAL, CBOE quoters will match the NBBO within the flash period or the order will be routed to the exchange showing the best price.

HALO: HAL on the Open (HALO) incorporates the NBBO on the open and uses the HAL process to address imbalances and trade as many contracts as possible on the open.

Preferred Market Maker: An order flow provider may designate any MM type in any designated Cboe Hybrid class as the "Preferred MM" for orders sent to Cboe.

SAL: The Simple Auction Liaison (SAL) is a mechanism that provides price improvement for marketable simple orders of 500 contracts or less. Available only in SPX.