The Master Co-Loader is responsible for closing the MBL. Co-Loader must close the Master Co-Loader's file relative to the HBL they have tendered. The party that files HBLs under the related parent BL is responsible for closing out the related parent BL (aka "Previous CCN"). In other words, the underlying co-loader that files the HBLs under the master loader is responsible for closing out the master loader's BL.