E) Custom rule classes for calculations

Typically the calculations of eligibility and entitlement stored in the isEligibleTimeline and objectiveTimelines rule attributes may involve complex business calculations, and CER rule classes can be created to structure these calculations in line with business requirements.

Any such rule classes do not need to adhere to any application-supplied interfaces (although the CER "extends" mechanism may be used to create a hierarchy of rule classes to treat rule objects in a polymorphic way if useful).

Some of the calculations will involve accessing stored data, by retrieving rule objects of these types:

rate cells (see F) RateRuleSet.RateCell rule objects and propagation configuration);
custom entities (see G) Custom Entity rule objects); and /or
custom evidence (see H) Custom Evidence rule objects.

Note: These retrievals cause a dependency to be stored between the case's determinationResult and the underlying stored data, which is how the Engine handles reassessment of cases when data changes (see Reassessment - Handling Changes in Circumstance.