I'm wading through editing a messy GEDCOM Import and find these all over. They are not present in a clean non-GEDCOM Profile.
It is part of the gedcom format that functions the same way a WikiTree ID does here. The gedcom import process is supposed to use that information to connect parents and children, but not display it as part of the biography or sources. Anne's answer about meaningless is right on - it should have been meaningful ONLY to a computer, not to a human being.