Good Requirements - Part VI - Traceability & Modularity

Have you ever found yourself having to respond to questions like:

• What requirement drove this feature?
• How did we implement this requirement?
• Is this requirement associated with others? Which ones?
• Can you show me how you met my needs?

Answering these questions is much easier when one's requirements are fully traceable. Traceability implies that requirements are uniquely identifiable and can be tracked. Traceability must go backward and forward (i.e., from user tests and design documents back through to high-level requirements and vice versa) for maximum benefit. Being able to show this, reinforces to the business community that their needs are understood and illustrates how they will be met.

The picture above illustrates how high-level requirements have been decomposed into low-level requirements. The screenshot is of Telelogic DOORS. The information in the High-Level Requirements column and the information in the Low-Level Requirements column exist within separate documents. Using this view, one can see whether there are low-level requirements defined for a high-level requirement. This will show one where work still needs to be done. The little arrows indicate that there is a link between a requirement and another one.

Another benefit of requirements management tools is the ability to see what requirements are affected when a requirement is changed. View the picture below and note that if one changed the Color Availability requirement one may possibly have to modify the 3 children of this requirement. Also note that the acceleration, emission standards and security features requirements (and their children) will not need to be modified.

I have found full blown start-to-end traceability to be a nightmarish task within MS Word and MS Excel. I strongly suggest that one makes use of the latest requirements management tools available. See my Good Requirements - Part IV - Be Consistent posting for some commercial products. Requirement management tools allow one to see the relationship between requirements and thereby manage them more effectively.