public function relateVersionEdits($oc)
    {
        $db = Loader::db();
        $v = [
            $this->getCollectionID(),
            $this->getVersionID(),
            $oc->getCollectionID(),
            $oc->getVersionID(),
        ];
        $r = $db->GetOne(
                'select count(*) from CollectionVersionRelatedEdits where cID = ? and cvID = ? and cRelationID = ? and cvRelationID = ?',
                $v
        );
        if ($r > 0) {
            return false;
        } else {
            $db->Execute(
               'insert into CollectionVersionRelatedEdits (cID, cvID, cRelationID, cvRelationID) values (?, ?, ?, ?)',
               $v
            );
        }
    }