Selecting a User ID

TSO/E and the z/OS operating system require that each user be assigned a unique user ID. This ID must be unique to the system's node, but can be a duplicate of another ID used by another node. The ID can either be chosen by the user or the system administrator depending on your installation's administrative guidelines. However, a number of operating system restrictions apply to the ID naming convention; your administrative policy may have defined others.

A user ID is often the user's name, initials, or department number, or any combination of valid characters you and the user choose with the following restrictions:

Length - no longer than seven characters
First character - must be an alphabetic (A through Z) character
Second through seventh character - any combination of alphabetic (A through Z) and numeric (0 through 9) characters. Special characters are not allowed.
With JES2 a user ID:
- Cannot be in the format Rnnnnnn or Nnnnnnn, where nnnnnn is a number in the range 1 through 999999. These identifiers are reserved for JES2-defined remote printers and networking nodes.
- Should not be in the format Unnnnnn, where nnnnnn is a number in the range 1 through 999999. These IDs should be reserved for local JES2 printer definitions; however, the actual range of numbers reserved is specified by your installation and may not be U1-U999999. Contact your JES2 system programmer if you need to define user IDs with this naming convention or refer to the LOCALNUM parameter on the JES2 OUTDEF initialization statement in z/OS JES2 Initialization and Tuning Reference.

When using education services in the Information Center Facility, a user ID of EQ is not allowed. The system programmer must provide a different user ID for any user of education services with that ID.