As it currently works, Fossil returns '0' on any command which succeeded, or '1' if the command was unknown or ambiguous.

It would be useful to be able to differentiate between 'no files were updated' and 'there was an error' in scripts.  Therefore I would like to request that "0" be returned when 'all is well', '1' when 'upd' or other command updated files on disk (adding, removing or updating), and '2' if there was a problem understanding the command.  Perhaps '3' if the command actually failed but was understood.