I'm not entirely sure but I think you refer to the Author and Copyright infos set in the menu of the mark IV. I think the camera stores these details in the EXIF metadata, not in IPTC.
If I'm right you have to have PM set your Photographer and Copyright fields using the {owner} and {user} variables. At the moment I cannot check it, as I don't have any mark IV photos with me that have the Author and Copyright infos set.
If I would be mistaken, then Kirk will put this straight.