The rules for logon names are:
- Local logon names must be unique on a workstation.
- Global logon names must be unique throughout a domain.
- The practical limit for a logon name is 64 characters, but the technical limit is 104 characters.
- A Pre-Windows 2000 logon name, up to the first 20 characters of the logon name, is assigned to all accounts (sAMAccountName).
- The Pre-Windows 2000 logon name must be unique throughout a domain.
- Logon names cannot contain / \ \[ \] : ; | " = , + * ? . While spaces are legal, DO NOT use them!
- Logon names are case aware BUT NOT case sensitive.