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.
1.
ERROR GOTO WHEREVER
Any number of procedure lines...
WHEREVER:
The next commands to be executed after an error...
2.
ERROR ERRFLAG=1
Sets the VISTA variable ERRFLAG to 1 upon an error.