Standard RIF must support normative rules
Standard RIF must be able to express normative rules. An example of such a rule is An EU-Rent customer can rent at most one car at a time, which defines restrictions within the business of the car rental company EU-Rent. Normative rules are also called structural rules in the business rules community and integrity constraints in the database community.
Position in the DC structure
Level: [Requirement] [PROPOSED]
Also, this requirement is found in the section on different types of rules of RIFUCR - List of Classified Requirements (with Duplicate Elimination) and in The requirements listed during the brain storming sessions at F2F2.
RIF without that is of limited use for me