I'm starting to work with the API and I see on the call to retrieve a user or multiple users one of the fields that is returned is user_type. So far I have only seen a value of "registered" come back and I was wondering what other values might show up and what they mean. In looking at the quarterly data dump I don't see a field on Users for user_type so does that mean all the users in that table are registered users? I'm guessing that it might have to do with people who used to be on StackExchange but dropped their account, but I wanted to make sure and not assume. Thanks in advance.

Chris