At one of the tools which are used in formulation of plan of project management, dividing project cost in detail, it is the cost block diagram which it expresses with layered structure.

Changeetc. for estimate with WBS the WBS element whichwas disassembled (the work package or the cost account) budget and estimate cost and actual cost (furthermore, according to need of the amount which a reliability and can there be) it allots, and can estimate manage costwise. In this case, it means to be the diagram where WBS that way shows cost structure.

But, for example financial accounting (cost accounting standard) and we would like to make the corresponding relationship of prime cost system of managerial accounting between cost structure of project clear it is, kind of when, WBS CBS of the structure which differs becomes necessary.