Q: How do I choose a user name and password?
A: Your user name and password must be between three and sixteen
characters long. User names and passwords are not case-sensitive: they can
be entered in either upper case or lower case. They can contain letters,
numbers, or some of each.
You may select any user name as long as it is not already taken by someone else.
If your preferred user name is already taken, you will be prompted to select an
alternative. (Adding a number to the user name you want is a good way to make it
unique). You may not use special characters (dot, slash, dash etc.) for your username.