在随后的项目费用管理中给出了答案(PMBOK 2004 3rd P158)，Control Account是项目费用核算的WBS单元，每个Control Account具有一个代码或者编号并与组织的会计体系对应。
Control Account 不仅是WBS的一个分解层次、费用管理中的一个核算单元，它更是项目管理中的一个 Control Point集成了scope, schedule, budget, actual cost, measurement of performance. 在组织中与其对应的是组织的某个组织分解结构(OBS) (PMBOK 2004 3rd P355). 基于Control Account的计划即为Control Account Plan，其中包含了明确的work, schedule和time-phased budget.(PMBOK 2004 3rd P356)
下面这些内容有助于更好的理解上面提到的Control Point:
To provide the responsible contract manager with technical, schedule, and other needed resource information, the management control system must be keyed to the same WBS element and organizational unit. The WBS level at which the management control system is established is primarily a function of the magnitude of the program and the type of product required by the contract. The responsible organizational level is a function of the company's management span of control and upper management's desire to delegate the responsibility for WBS elements to lower management levels. In identifying control accounts, the contractor is expected to establish organizational responsibilities at meaningful and appropriate levels. Otherwise, the contractor's existing management control systems and responsibility assignments may be affected adversely.
Virtually all aspects of the contractor's management control system (i.e. technical definition, budgets, estimates, schedules, risk management, work assignments, accounting, progress assessment, problem identification, and corrective actions) come together at the control account level. Performance visibility is directly relatable to this level of detail.
As the end product is subdivided into smaller subproducts at lower WBS levels, the work effort required by each element can be identified and assigned to functional organizational units. (注:前面一句又解释了WBS是面向可交付成果的 PMBOK 2004 3rd P112)The contractor will assign management responsibility for technical, schedule, and other performance criteria at lower levels within the WBS. The management control system will keep the lower levels of the WBS visible as it interfaces with the organization. At the juncture of the WBS element and organization unit, control accounts are established and performance is planned, measured, recorded, and controlled. To this end, the technical requirements for the work and work product must be specified; the work scheduled, budgeted, and performed; and attainment of specified technical requirements verified.
