Maintain bidirectional traceability among requirements and work products.


The intent of this specific practice is to maintain the bidirectional traceability of requirements. (See the definition of “bidirectional traceability” in the glossary.) When requirements are managed well, traceability can be established from a source requirement to its lower level requirements and from those lower level requirements back to their source requirements. Such bidirectional traceability helps to determine whether all source requirements have been completely addressed and whether all lower level requirements can be traced to a valid source.

Requirements traceability also covers relationships to other entities such as intermediate and final work products, changes in design documentation, and test plans. Traceability can cover horizontal relationships, such as across interfaces, as well as vertical relationships. Traceability is particularly needed when assessing the impact of requirements changes on work activities and work products.

In a service environment, you should be able to trace stakeholder requirements to the elements of the delivered service and supporting service system that were developed from those requirements or other requirements derived from stakeholder requirements. Conversely, elements of the delivered service and supporting service system should be traceable back to the stakeholder requirements they meet.


Examples of what aspects of traceability to consider include the following:
  • Scope of traceability: The boundaries within which traceability is needed
  • Definition of traceability: The elements that need logical relationships
  • Type of traceability: When horizontal and vertical traceability is needed
  • Integrated service environment: The scope of traceability applied in an organization in which tangible products or product elements are integral elements of services and services are the primary focus of the organization

Such bidirectional traceability is not always automated. It can be done manually using spreadsheets, databases, and other common tools.

Example Work Products

  1. Requirements traceability matrix
  2. Requirements tracking system


1. Maintain requirements traceability to ensure that the source of lower level (i.e., derived) requirements is documented.

2. Maintain requirements traceability from a requirement to its derived requirements and allocation to work products.

Work products for which traceability may be maintained include the service system architecture, service system components, development iterations (or increments), functions, interfaces, objects, people, processes, and other work products.

3. Generate a requirements traceability matrix.

A traceability matrix might have the list of stakeholder requirements and derived requirements on one axis. The other axis might list all of the components of the service system, including people and consumables. The intersections of the rows and columns would indicate where a particular requirement applies to the parts of the service system.