A Combined Highway Document includes a Highway Cargo Document (identified by a CCN) and a Highway Conveyance Document (identified by a CRN) into a single document for easier data entry.

Note: If you wish to check the status of your Combined Highway Document, you must check the Highway Cargo Document and Highway Conveyance Document statuses separately as they are processed as separate Trade Documents.

Please refer to section 6.3.2 (Creating a Combined Highway Document) of the eManifest Portal User Guide for more information.
http://www.cbsa-asfc.gc.ca/prog/manif/portal-portail/guide-eng.html