Breakdowns such as System Engineering, Software Engineering, and Hardware Engineering are seen often. The functional WBS is used in organizations that are heavily involved in the functional aspect of business. Of course, there are hybrids of these, but they still rely heavily on either one or the other of these two basic WBS types. There are actually only two basic types of WBSs used within industry today: the Functional and the Deliverable (product) types.
Remember that the definition of a project is a “unique” endeavor therefore, while one WBS could be used as a starting point, I can assure you that the entire WBS cannot be used to fully describe your project. There are several references available to use as guidelines for kick-starting the development of the WBS (e.g., PMI-WBS, MIL-HDBK-881). Development of a proper WBS is the backbone for a proper schedule. Without the WBS, the work to be accomplished will flounder and the schedule will be unorganized and for the most part not executable. The most crucial part of any schedule is the proper development of the work breakdown structures (WBS).
The basic construction of a schedule revolves around a proper approach to its development. Regardless of these various outlooks, however, the question that should be the primary focus is: “Is the schedule executable?” Many organizations and experts have their opinions on what constitutes a well-built schedule. There are a great number of different aspects to a schedule.