None
There is no preferred or mandatory employee
Preferred
This is one of possibly several preferred employees
Mandatory
This is one of possibly several mandatory employees
PreferredOrdered
There is more than one preferred employee and this one is more preferred than those marked as ‘Preferred’.
MandatoryOrdered
There is more than one mandatory employee and this one is more preferred than one marked as ‘Mandatory’
MandatoryNot
This is one of possibly several (up to 10) employees who should not be used
