Time-qualified rule

A time-qualified rule is a circumstance that is only rule resolved during a specified range of time. This type of rule is commonly referred to as a "date range circumstance" or "temporary rule".

A date range uses a start date and time and an end date and time. If the system's current time falls before or after this window, the time-qualified rule is invisible to rule resolution. A date range circumstance is different from a date property circumstance which evaluates the date value of a property (not the system time).

To create a circumstance that uses a date range, see Completing the Specialization form.

Restrictions

Date range circumstances may only be created for supported rule types. This is controlled by the Allow rules that are valid only for a certain period of time checkbox on the Class form.
You cannot override a final rule with a time-qualified rule.
When time-qualified rules are used in a multinode system, be sure to synchronize the internal clocks of all the server nodes in the cluster. Clock differences of less than a few seconds may lead to incorrect application results. Most operating systems offer facilities for such synchronization.

Using more than one date range circumstance

Your application can include multiple date range circumstances for the same base rule with overlapping (but not identical) date and time intervals. At run-time, rule resolution processing finds all the time-qualified rules with an interval that includes the current date and time. It then selects the "best" rule to run based on the following tests:

Examine the End dates on each candidate time-qualified rule. Choose the rule or rules that have the nearest End date, discarding others.
If only one candidate remains, that rule is the result of this phase of rule resolution processing
If two or more candidates remain, the one with the most recent Start date is selected.

	as-of-date processing, base rule, circumstance, rule resolution
	Complete the Specialization Form Contrasting time-qualified rules, date-time circumstances, and historical processing

Definitions