In much earlier versions of the MAPDL program, the *REPEAT command function was accessed by the command RPnnnn, where nnnn was the number of times to repeat the previous command. In R6.1, changes were made to the program logic that interprets (parses) the command line. Any command line that starts with RP is processed as the old RPnnnn command. In the *USE command notes, the last paragraph states: “Note, since undocumented commands exist in the MAPDL program, the user should issue the command intended for the macro file name to be sure the ‘unknown command’ message is output in the processor where it is to be used.” Running R6.1 in an empty directory and issuing RPM in PREP7 does not give the “unknown command” message. We recommend against using an unknown command macro with any name that starts with RP, as RPnnnn is an undocumented command.