This is a PPWIZARD command line switch.
By default when one or more warnings are displayed a return code of 1 will be returned.
You can use this switch to set any return code you like (the default is 1).
When you supply a value of 0 it indicates that you don't care what warnings were displayed, you do not consider a warning to be an error.
You can get more fine tuning with the Warnings option.