I agree with Ashwin, but I can see how that phrase in the PMBOK could be somewhat confusing. It seems to imply that you are using software that has a direct electronic tie between the WBS and the accounting software. This is not necessarily the case!
The control accounts are merely the level of your WBS at which you choose to track costs and perform your EVM calculations. For sizable projects it would be prohibitively time consuming and expensive to try to track everything at the work package level (which is the bottom/most detailed level of your WBS).
Since the control accounts are where you are calculating EVM and other financials, of course they are "linked" to the accounting system. Just keep in mind that the link is not necessarily an automatic electronic transfer of data.
Moderators: Yolanda Mabutas, Ahmed Amin, Scott Gillard, Mary Kathrine Padua, ERIC BARTLETT, Gail Freedman, Kevin Nason, Steven Mudrinich, PMP, Mark Wuenscher, PMP, John Wolverton, Tracy Shagnea, PMP, Jada Garrett
This interview with Simona Fallavollita (LinkedIn Profile) was recorded at the magnificient Project Management Institute (PMI)® Global Conference 2017 in Chicago, Illinois. We discuss the how, what, why and when of the changes that are coming to the PMP exam.