7.1 Introduction

So often, the real rationale for a particular design and the deeper understanding of how the components of a system work together to achieve an end result remain in the minds of the engineers. Months or years later, when the original designers have long since moved on, or their memory has dimmed, the loss of that understanding may seriously impede the ability to evolve, maintain or reuse the system.

This chapter first presents a technique for maintaining this greater understanding of a system, through capturing the rationale associated with the relationships between problem, solution and design. Christened "rich traceability", the approach builds on the basic concepts of "elementary traceability" presented in Chapter 1 and applied in subsequent chapters.

While rich traceability may represent one big side order of "Why?", the "Wither?", "Whence?" and "Wherefore?" of traceability are perhaps addressed through another subject of this chapter: metrics in relation to traceability.

7.2 Elementary Traceability

There are many ways of representing many-to-many relationships. One consultant visited a defence contractor just prior to a customer traceability audit to find the office all laid out ready. Along the length of the floor on one side was spread out the requirements document and on the other side the code listing. Traceability was shown by pieces of...