NicC wrote:ADDUSER is not a TSO command but you are passing it to TSO. It is a RACF command - RACF is not TSO.
ADDUSER is a TSO command provided with the IBM RACF product. So you can say it is both a RACF command and a TSO command.
You get the IKJ56621I INVALID COMMAND NAME SYNTAX message if there is something wrong with the command name; 1234 entered as a TSO command will give this message. I suspect the real problem is elsewhere since I don't see anything obviously wrong with the ADDUSER command in the initial post. I have run the ADDUSER command in TSO CLISTs (I don't do Rexx) with no problem.