A reservation is a hold placed against an account. Before a job runs, a reservation (or hold) is made against one or more of the requesting user's applicable account(s). Subsequent jobs will also post reservations while the available balance (active allocations minus reservations) allows. When a job completes, the reservation is removed and the actual charge is made to the account(s). This procedure ensures that jobs will only run so long as they have sufficient reserves.
Associated with a reservation is the name of the reservation (often the job id requiring the reservation), the user, project, and machine as applicable, an expiration time, and an amount. Operations include creating, querying, modifying, and deleting reservations.