This page contains Appendix B of the paper ""Defining Business Rules ~ What Are They Really?", produced by the Business Rules Group. Other formats in which this paper is available are described in Defining Business Rules -- What Are They Really? (Abstract & Table of Contents)

Defining Business Rules ~ What Are They Really?

Appendix B - How to Read a Conceptual Model

The conceptual models in this document have been portrayed using the IDEF1X notation, with a specific convention for relationship names. Each relationship, in each direction, is intended to be read as a normal English sentence in the form:

Each <entity-1> {must be | may be} <relationship> {one and only one | one or more} <entity-2>.

Both relationship names appear next to the relationship line, and they are intended to be read in a clockwise direction. The relationship symbols are as follows:

For example, the following model . . .

. . . contains the following two sentences:

• Each text ordering must be a possible wording of one or more facts.
• Each fact must be expressed as one and only one text ordering.

In the drawings, round cornered rectangles represent either subtypes or associative (intersect) entities.

A subtype entity is a set of occurrences of a supertype entity. All attributes of and relationships with a supertype are 'inherited' by the subtype, but each subtype may have its own relationships and attributes unshared with other subtypes. In the IDEF1X notation, an entity may have more than one 'cluster' of subtypes. An occurrence of one subtype may not also be an occurrence of any other subtype in the same cluster.

Where all occurrences of the supertype are also occurrences of one of the subtypes in a cluster (that is, the cluster is described completely), the symbol used is:

If the set of subtypes do not exhaustively describe all occurrences of the supertype that are in a cluster, the symbol looks like this:

In this document, the model may show a complete cluster, but a view being described in a particular chapter may not show all the subtypes. In this case, the incomplete view is shown with a dotted line to the side (as illustrated below) to indicate that not all subtypes are shown in the view.

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