      Unlike Nasdaq over the counter trading, listed trading follows a verydifferent set of rules. To effectively trade the listed markets, a thoroughunderstanding of both the types and methods of execution as well as therules associated with them is necessary. Executions of listed trades (evenover the SuperDot) are generally slower than Nasdaq over the countertrades. The reason for this is that a human being is calling out all ordersto the "crowd" of brokers on the floor before actually pairing them off.This takes time. It is not to say that fills will be less than desirable onlisted trades. Quite to the contrary — because of the specific rulessurrounding the order in which trades are filled, you will get the bestfills possible (in the absence of having your own floor broker) using theSuperDot system.