What does this icon mean next to a user account in the legacy User Manager?

Note: The legacy User Manager was deprecated in version 11 and was removed in version 12. This FAQ  entry only applies only to Cerberus version 10 and below.

In the legacy User Manager, several different icons can appear next to a user account in the User Manager. 

User Accounts

Here below is what the icons represent. 

User Account Icon Legend