An advance reservation is the mechanism by which Maui guarantees the availability of a set of resources at a particular time. Every reservation consists of 3 major components, a list of resources, a timeframe, and an access control list. It is the job of the scheduler to make certain that the access control list is not violated during the reservation's lifetime (i.e., its timeframe) on the resources listed. For example, a reservation may specify that node002 is reserved for user Tom on Friday. The scheduler will thus be constrained to make certain that only Tom's jobs can use node002 at any time on Friday. Advance reservation technology enables many features including backfill, deadline based scheduling, QOS support, and meta scheduling.