SBVR14 — Note for Rule

The current definition of “rule” in SBVR, while very precise, is opaque for practitioners. (The definition for “business rule” offers no help.) SBVR should be more definitive about the real-life sense/role/purpose of rules. It should also emphasize early-on the crucial distinction between necessities and obligations.

The SBVR v1.3 definition of “rule” in SBVR is:

proposition that is a claim of obligation or of necessity

SBVR Issue 19840 proposes a change to the definition. Regardless of the specifics of the changes made under that Issue, a precisely-crafted (fully formal) definition of 'rule' can be opaque for practitioners. To communicate, in real-world terms, the sense/role/purpose of rules the following Note is added to the entry for 'rule':

Note: Rules fall into two fundamental categories, as follows:

• A behavioral business rule indicates something people or organizations are either obliged to do (an obligation), or prohibited from doing (a prohibition). A behavioral business rule serves to shape conduct or action and to provide a basis for judging the propriety of behavior.

• A definitional rule indicates either what is always the case (a necessity) or is never the case (an impossibility). A definitional rule serves to specify a condition, in addition to those specified in the definition of the concept, that is true for every instance of the concept(s) to which the rule applies.
As such it can be used as the basis for inference.