A trading model associated with firm, executable bids in a transparent order book. Trading is anonymous and participants can trade with anyone on the platform with firm pricing. This model is associated with listed and highly standardised over-the-counter (OTC) products where competitive pricing and deep liquidity allows for completely transparent bids and offers. Only the most liquid OTC derivatives, such as long-dated IRS and Foreign Exchange transactions, are suitable for order book trading at present. Trade frequency for less liquid markets is too low to allow the continuous stream of prices a CLOB needs to function. For a common trading model which is associated more with less liquid markets, see 'request for quote (RFQ)'.