The following video will help you create users and get them set up in the system.
How to Control Access using User Attributes
User Attributes without a value (empty) should be taken into account when using a negative condition to control access.
A => Department - is - Help Desk
B => Department - is - Consultant
C=> Department - is Empty - true
To disallow consultants and help desk employees but allow users with no department. The condition should be:
NOT (A OR B) OR C
The number of allowed user attributes used to control access to the site (such as email, password, title, department) is limited to 78.