The WBS will be developed and maintained based on the systems engineering efforts throughout the system's life cycle. This term identifies the elements that are applicable to all seven major systems. The top three levels are specified in a work breakdown structure. Level 1 is usually directly identified as a program or a sub-element of a program. Level 3 elements are elements subordinate to level 2 major elements.
Lower levels follow the same process.
The program WBS is the structure that encompasses an entire program. The program WBS has uniform terminology, definitions, and placement in the product-oriented family tree structure. The contract WBS is the complete work breakdown structure for a contract. It includes the DOD-approved program WBS extended to the agreed contract reporting level and any discretionary extensions to lower levels for reporting or other purposes. This comprehensive work breakdown structure forms the framework for the contractor's management control system.