What do we consider user data (aka user attribute)?
A user attribute is an attribute that reveals or may reveal a person’s identity, personal characteristics, contact information, or affiliation/role/access authorization.
When a user accesses an online resource via federated single sign-on, the resource provider often needs a minimum amount of information about that person in order to verify that person has the proper access authorization. It may also use the user data to send notifications and to allow the user to personalize their experience.
These user data can be loosely grouped into three categories: person identifiers, person characteristics/contact information, and authorization support information.
The Working with user data section of the InCommon Federation Library wiki documents the user data elements in common use within the Federation. It also provides guidance and strategy on making the most of user data, the right way.