The preprocessing call

Before RACF® makes the preprocessing call to IRREVX01, it parses the command to ensure that it is syntactically correct. If RACF cannot successfully parse the command, it does not give control to the exit. If the command was issued as a RACF operator command, RACF verifies that the user is allowed to issue the command as an operator command based on the OPERCMDS authority check. If the user does not have the required authorization, RACF does not give control to the exit.

RACF does not process the naming convention table before making the preprocessing call. Therefore, data set names in the command buffer might be changed later by the naming conventions.

For commands that specify the AUTOUID or AUTOGID keyword, the command image contains only the AUTOUID or AUTOGID keyword. The derived UID or GID value is contained in the command image that is sent to the postprocessing call.

Based on the information passed to it in the parameter list, the exit routine can:

Make changes to the command before the command executes, by updating the command image passed to it.
Determine whether the command executes or fails, by setting a return code in register 15, as described in Registers at exit. If the routine returns a nonzero return code, the command fails with a return code of 8.
Determine whether RACF issues message IRRV022I for a failed command, by setting a return code in register 15, as described in Registers at exit. The exit routine has the option to provide text to be appended to message IRRV022I.

If the exit routine makes a change to the command buffer in the preprocessing call, RACF parses the command again. RACF does this parse in noprompt mode, to prevent the user from entering values or adding keywords that the exit would find unacceptable. If this parse fails, or if RACF finds that the exit routine changed the command name, RACF fails the command and calls the exit routine for the postprocessing call, to allow the exit to clean up and reset values set by the preprocessing call.