Allotments can be purchased for a specific period of time such as a whole season, part of a season or for any single dates and then resold to travel partners and final customers around the globe. A couple of days prior to carrier departure/hotel check-in any unsold seats/rooms may be released back to the supplier if such an agreement exists between the two parties. An allotment release back period is also negotiated as part of the allotment contract (e.g. four days prior to check-in/departure