As part of eligibility and entitlement processing, the eligibility and entitlement engine must create decisions over a period of time. This period of time is defined by a from and to date passed into the eligibility and entitlement engine. To create these decisions, the eligibility and entitlement engine uses a list of dates. This list of dates can either be provided to the eligibility and entitlement engine or the eligibility and entitlement engine can work out these dates. The former is referred to the "Event Date List"; the latter as the "Pattern Date List". In addition to standard create decision processing, there is also the ability to add custom processing.