public function checkConnection($SourceID, $TargetID)
    {
        if (isset($this->Data[$SourceID]["Connections"])) {
            foreach ($this->Data[$SourceID]["Connections"] as $ConnectionID) {
                if ($TargetID == $ConnectionID) {
                    return true;
                }
            }
        }
        $this->Data[$SourceID]["Connections"][] = $TargetID;
    }