(unknown) value

there is possible to use “(unknown)” value in scripts like:
/queue simple remove [find parent=“(unwnown)”];
?

now i do that like

:foreach que in=[/queue simple find ] do={
	:local queName [/queue simple get $que name ];
	:local queParent [/queue simple get $que parent ];
	:if ( $queParent = "(unknown)" ) do={
		:log info "$queName wrong parent"; 
	}	
}

I am testing and is working for me, but a try with queue tree.