Currently only the User ID, First Name and Last Name are rquirements.  So this allows my Tiered Admins to add users to the Vocera system without adding the new user to an appropriate group.  In our environment, it would be extremely helpful to force the tiered administrators to add the user to one of the groups they manage.  Fields that should be considered for Admins to have the flexibility to require from the Tiered Admins include:
Add user to at least one group
Employee ID
Cost Center
Email Address