Empty–full (Empty For Full) is a type of contract that calls for the purchase in advance of a certain number of rooms (or other category of services, e.g. seats on charter flights) for a defined period, regardless of what the actual occupation of these will be.
The hotelier (or another supplier) is obliged to make available to the travel company a certain quota of rooms, while the latter agrees to pay a flat rate fee. There is no release clause: both parties are reciprocally bound by the agreement and are so throughout the effective period of the same. The travel company is obliged to pay the agreed room price even if the room is unsold. It is the basic formula working for tour operators.