What is a definitional rule?

A definitional rule (also known as a structural rule) shapes concepts, creates knowledge, or computes information. It provides the criteria for classification or calculation, representing the operational knowledge of an organization. For example, "A customer is classified as a 'Preferred Customer' if they have made more than ten purchases in a calendar year." This rule defines what a 'Preferred Customer' is. By their nature, definitional rules cannot be violated; something either meets the definition or it does not. They establish the fundamental truths and vocabulary of the business domain.

B. An obligation or prohibition of conduct, action, practice, or procedure: This describes a behavioral rule (or operative rule), which guides conduct and can be violated.
C. A rule that can be violated: This is a characteristic of a behavioral rule, not a definitional rule. Definitional rules establish facts and cannot be violated.
D. A representation of the behavior of people: This is too narrow and describes a subset of behavioral rules. Business rules apply to systems, processes, and the organization, not just people.

1. International Institute of Business Analysis. (2015). A Guide to the Business Analysis Body of Knowledge (BABOK Guide) (Version 3). IIBA. Section 10.8.2

"Elements

" describes Definitional Rules as those that "shape concepts or produce knowledge or information" and represent "operational knowledge of the organization." It explicitly contrasts them with Behavioral Rules.

2. Bleistein

S. J.

Aurum

A.

& Cox

K. (2006). Linking requirements and architecture: a study of a GSD project. In Proceedings of the 2006 international workshop on Global software development for the practitioner (pp. 15-21). ACM. This paper discusses the classification of business rules

aligning with the IIBA's distinction

noting that definitional rules (structural rules) establish the vocabulary and facts for a business domain. (DOI: https://doi.org/10.1145/1138506.1138511)

3. Carnegie Mellon University

Heinz College. (2021). 95-713: Object-Oriented Analysis and Design Courseware

Lecture 4: Requirements Elicitation. Slide 23

"Business Rules." The course material

referencing the BABOK

categorizes rules into Definitional and Behavioral

defining the former as shaping concepts and the latter as constraining behavior.