The key to the System Engineering process is the idea that we are always accountable to someone, for something. The project is accountable to the business for business results that satisfy the business objectives. We verify results against requirements. Each layer of increasingly more detailed requirements, specifications and designs is validated against the higher levels to provide assurance that they are collectively necessary and sufficient to meet the business objectives. The same basic engineering concept applies as much to brick and mortar construction as it does to system development and implementation. Each level of requirements is traceable to the next higher level. Each test or inspection is traceable to a requirement. Each requirement is verified by at least one test or inspection. This is the essence of System Engineering - being conscious of how every detail is interrelated to every other, how each may be verified or validated, and how they are all traceable to the bigger picture.