A Windows NT computer name can be up to 15 alphanumeric characters with no blank spaces and must be unique on the network. It can contain the following special characters:

! @ # $ % ^ & ( ) - _ ' \{ \} . 623

It may not contain:

\ * + = | : ; " ? ,

If you have non Windows NT clients, I would restrict the name to 12 alphanumeric characters.

DNS does not like

% # _ and some applications do not like - so I wouldn't use them.

I personally only use alphanumeric characters.

Do NOT use all numeric characters.