A hierarchical organization of all the work (effort) required to complete a project. See MIL-STD-881 and follow it. It is conceptually complete and cogent.
It is sometimes supposed that a WBS should follow the contractor’s organizational structure (hierarchy of managers), because it is easier to see how the tasks rack-and-stack to the organization. The notion is well-refuted in the reference. I made the mistake (once, and once only) of suggesting to one of MIL-STD-881’s original authors1 that some people felt the two hierarchies should align. He was a retired US Army Major General…see wirebrushing.
Footnotes- At least, he claimed to be…and the retired four-star he worked for was sitting right there…as were two other retired three-stars…and none of them contradicted him.[↩]