Limit Order Book
A record of unexecuted limit orders maintained by the specialist.
Investopedia Commentary
The specialist has the responsibility to guarantee that the top priority order is executed before other orders in the book, and before other orders at an equal or worse price held or submitted by other traders on the floor (floor brokers, market makers, etc).
Related Links
The Basics Of Order Entry
See also: Limit Order, Market Order, Order, Specialist, Stop Order