public function isAlias($c = null)
    {
        if ($c) {
            $db = Loader::db();
            $cID = $c->getCollectionID();
            $vo = $c->getVersionObject();
            $cvID = $vo->getVersionID();
            $q = 'select bID from CollectionVersionBlocks where bID = ? and cID=? and isOriginal = 0 and cvID = ?';
            $r = $db->query($q, [$this->getBlockID(), $cID, $cvID]);
            if ($r) {
                return $r->numRows() > 0;
            }
        } else {
            return isset($this->isOriginal) ? (!$this->isOriginal) : false;
        }
    }