In the same way on IT we have capacity plans for data storage, server capacity and other forecasting processes, on the supply chain processes there is the RCCP.
RCCP verifies that you have sufficient capacity available to meet the capacity requirements for your master schedules. Typically there is an application that implement these processes.
Marketing/sales department and production department use this data to balance required and available capacity, and to negotiate changes to the master schedule and/or available capacity. Basically your rough cut capacity plans are a statement of the capacity required to meet your gross production requirements.