Some info -
From docs.sun.com:
http://docs.sun.com/ab2/coll.47.4/SY...Enc=iso-8859-1

User (Login) Names
User names, also called login names, let users access their own systems and remote systems that have the appropriate access privileges. You must choose a user name for each user account you create. User names must:

Be unique within your organization, which may span multiple domains

Contain from two to eight letters and numerals (the first character must be a letter and at least one character must be a lowercase letter)

Not contain an underscore or space


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You can have a username longer than what is documented. I tested on a Solaris 2.6 system and found that the following worked with no problems

userids12red

I also tried userids12 as a login since the documentation says it's a max of 8 characters, but I could not log in (believing that the system should see the first 8 characters and let me in anyway)