Valid Characters for CMDPREFIX › The Command Prefix String

The Command Prefix String

The command prefix string can be one to eight characters. You should not choose a command character prefix string that will conflict with a command, an abbreviation of a command, or a command invocation. You should not define a command prefix string such that the prefix is either a subset or a superset of an existing prefix with the same first character.

For example, if !MIM is already defined as a command prefix, then !, !M, and !MI are subsets of and conflict with the original command prefix string. Likewise, !MIM1 and !MIMM also conflict with the original command prefix string because they are both supersets of the first command prefix string. The z/OS DISPLAY OPDATA command can be used to determine all previously registered command prefix strings in the running system.