Editing Work breakdown structure (section)

=== Terminal element ===
The lowest element in a [[Tree (data structure)|tree structure]], a terminal element, is one that is not further subdivided. In a Work Breakdown Structure such elements (activity or [[deliverable]]), also known as work packages, are the items that are [[Estimation (project management)|estimated]] in terms of [[Resource management|resource requirements]], [[budget]] and duration; linked by [[Dependency (project management)|dependencies]]; and schedule. At the juncture of the WBS element and organization unit, control accounts and work packages are established, and performance is planned, measured, recorded, and controlled.<ref>MIL-STD-881C, Work Breakdown Structures for Defense Materiel Items, 3 October 2011, ¶3.1.4</ref> A WBS can be expressed down to any level of interest. Three levels are the minimum recommended, with additional levels for and only for items of high cost or high risk,<ref>MIL-STD-881C, Work Breakdown Structures for Defense Materiel Items, 3 October 2011, ¶1.4.1</ref> and two levels of detail at cases such as systems engineering or program management,<ref>MIL-STD-881C, Work Breakdown Structures for Defense Materiel Items, 3 October 2011, ¶2.2.4.2</ref> with the standard showing examples of WBS with varying depth such as software development at points going to 5 levels<ref>MIL-STD-881C, Work Breakdown Structures for Defense Materiel Items, 3 October 2011, ¶Fig.3-6</ref> or fire-control system to 7 levels.<ref>MIL-STD-881C, Work Breakdown Structures for Defense Materiel Items, 3 October 2011, ¶Fig.3-1</ref>