Unclear text about "relationships reordered" in api dox of QContactManager::saveContact()

From http://doc.qt.nokia.com/qtmobility-1.2/qcontactmanager.html#saveContact:
"If the contact has had its relationships reordered, the manager will check to make sure that every relationship that the contact is currently involved in is included in the reordered list, and that no relationships which either do not involve the contact, or have not been saved in the manager are included in the list. If these conditions are not met, the function will return false and calling error() will return QContactManager::InvalidRelationshipError."

What is meant with "relationships reordered". Which "reordered list"? The data as returned by QContact::relationships()? Does that mean that an API client can save also relationships by passing them somehow with the contact? But then QContact has no setRelationship(...) method.

Sorry, but this whole text is not really understandable to me, so on implementing the qtcontacts-tracker engine we are unsure if we miss to do anything in the reimplementation of QContactManagerEngine::saveContact(...) and friends.
Please find a better description