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Value Constraint Checking

Many FRSs provide some sort of run-time slot-value constraint checking. Each time a slot value is changed (either locally, or through a change to inherited values), the FRS evaluates constraints that have been defined by the user to specify what values are allowable for a given slot.

Constraint checking is described by two behaviors: :constraint-checking-time controls when constraint checking should be performed, and :constraint-report-time controls when constraint violations should be reported to the user, as follows.

Allowable values of :constraint-checking-time are:

Acceptable values of :constraint-report-time are:



  • Peter Karp