A diagram showing the associations between subject areas and providing a high-level view of the data of the enterprise.
The subject area association -- involving subject area (times 2) and the reason for association -- is recorded. Example:
A diagram that represents entity types, the relationships between them, and their organization into subject areas and the relationships between them.
Using the Entity Relationship Diagram Created During the ISP
At the start of Business Area Analysis, an entity relationship diagram exists if Information Strategy Planning was carried out. This diagram documents entity types in subject areas included in the business area. The diagram will be steadily investigated and expanded throughout Business Area Analysis. It often happens that the end result is no longer a good match to the starting set of subject areas -- some may no longer be needed; others may be too big. It is therefore useful to re-form subject areas by grouping the results of Business Area Analysis.
Producing the Subject Area Entity Relationship Diagram
A subject area entity relationship diagram is produced by re-forming subject areas implied by an entity relationship diagram to reflect new knowledge of the data in a business area. A subject area entity relationship diagram consists of a set of entity relationship objects organized hierarchically into subject areas. The main constituents of a subject area entity relationship diagram are entity types, (possibly new) subject areas associated with the subject entity types, and relationships. There may be a hierarchy of diagrams. Every diagram in the hierarchy represents the constituents of some higher-level subject area. At a high level, there may be only subject areas represented in the diagram, so it is then known simply as a subject area diagram. Example:
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