This is a PPWIZARD command line switch.
This switch allows you to specify a command which will be executed immediately.
Normally the command output is hidden and captured if in debug mode. To see the output preceed the command with the '!' character.
If "RcTest" is not supplied then the return code is ignored otherwise it is a rexx expression where the rexx variable "CmdRc" holds the commands return code. A boolean result is expected with TRUE meaning the validation was successful.