There are many relationships between requirements and other requirements and between the requirements and the system design. There are also links between requirements and the underlying reasons why these requirements were proposed. When changes are proposed, you have to trace the impact of these changes on other requirements and the system design. Traceability is the property of a requirements specification that reflects the ease of finding related requirements.
There are three types of traceability information that may be maintained:
- Source traceability information links the requirements to the stakeholders who proposed the requirements and to the rationale for these requirements. When a change is proposed, you use this information to discover the stakeholders so that they can be consulted about the change.
- Requirements traceability information links dependent requirements within the requirements document. You use this information to assess how many requirements are likely to be affected by a proposed change and the extent of consequential requirements changes that may be necessary.
- Design traceability information links the requirements to the design modules where these requirements are implemented. You use this information to assess the impact of proposed requirements changes on the system design and implementation.