ERROR tells VISTA to execute the given VISTA command whenever an execution
error occurs. The command can be any VISTA command but is quite often a
GOTO command. VISTA_command can not contain multiple commands separated
by semicolons.
ERROR GOTO WHEREVER Any number of procedure lines... WHEREVER: The next commands to be executed after an error...
ERROR ERRFLAG=1 Sets the VISTA variable ERRFLAG to 1 upon an error.