public function GetFieldMaps($objectclass)
	{
		// this is a temporary ram cache
		$fms = $this->_mapCache->Get($objectclass."FieldMaps");
		if ($fms) return $fms;

		$this->IncludeModel($objectclass);

		if (!class_exists($objectclass."Map")) throw new Exception($objectclass . " must either implement GetCustomQuery or '" . $objectclass."Map' class must exist in the include path.");
		$fms = call_user_func( array($objectclass."Map","GetFieldMaps") );

		$this->_mapCache->Set($objectclass."FieldMaps",$fms);
		return $fms;
	}