Two types of captions are available (supported for recording):
CEA-608, SD only: it is read directly from Line 21 of the picture data (= first visible line. Note the white "blocks" in the picture – these are encoded closed captions). It is being extracted from the picture and written as a closed captioning track into the QuickTime movie.
CEA-708, HD only: it is read from VANC Line 9, which is not a visible line. It is directly copied as a SMPTE334M packet into the closed captioning track of the QuickTime or MXF Op1a file.
No special setup is required. If you see the CC logo (please see screenshot below) in the Bottom Bar of the Channel Viewer, Closed Captions are being recognized and recorded, either into the MOV, MXF or SCC sidecar file (requires a dedicated Destination Preset).