How do you make the Filter so we can use the FIM cmdlets to list Users who have no Manager attribute

Question

I can easily create a Set of Users who are "unusual"
The SET criteria is
EmployeeID starts with %
and Any of
    EmployeeStatus not starts with %
    EmployeeType not starts with %
    Manager not in All FIM users
This criteria works and gives me all the users when I push the View Members button.
But when I look at the Set's Filter it seems to refer to a uuid of that All FIM users Set. To be honest I dont fully understand the set's XPATH filter.
What I hope to do is to some how build a filter so that the FIM cmdlets can be used to identify and fix up these users, especially those who do not have a valid Manager. There are hundreds of these non-standard users and although possible, its not practical
to do this by hand via the "All Non Standard Users" set.
Any hints welcomed.

Answer 1

All users without a manager: Xpath Filters
/Person[not(Manager=/Person)]
or,
/Person[Manager!=/Set[DisplayName='All People']/ComputedMember]
<# Please do not anything in the production environment unless and until you are very much sure #>
# Powershell Cmdlet to find all users in portal not having manager
# Load FIMAutomation module
 if(@(Get-PSSnapin | ? { $_.Name -eq "FIMAutomation" } ).Count -eq 0)
     Add-PSSnapin FIMAutomation;
$users = Export-FIMConfig -customConfig "/Person[not(Manager=/Person)]" -Uri "http://localhost:5725"  -OnlyBaseResources
foreach ($user in $users)
$x = (($user.ResourceManagementObject.ResourceManagementAttributes | Where-Object {$_.AttributeName -eq "DisplayName"}).Value) 
Write-Host "$x"
Thanks and regards,
Anirban Singha(Bangalore)