BCWS is used in Earned Value Analysis

It is the cumulative cost of doing work as defined in the Base programme.

For a fuller understanding, this Wiki entry should be read in conjunction with ACWP and BCWP.

The total value of the activities are added up for each period and plotted cumulatively to give a profile on a graph.

Further info can be found at:

http://www.projectsplanning.com/Projects%5FPlanning/Terminology/Terminol...