-If the error flag is not set then perltidy ran to completion. However there
-may still be warning messages in the B<stderr> stream related to control
-parameters, and there may be warning messages in the B<errorfile> stream
-relating to possible syntax errors in the source code being tidied.
+A exit value of 0 indicates that perltidy ran to completion with no error messages.
+
+An exit value of 1 indicates that the process had to be terminated early due to
+errors in the input parameters. This can happen for example if a parameter is
+misspelled or given an invalid value. The calling program should check for
+this flag because if it is set the destination stream will be empty or
+incomplete and should be ignored. Error messages in the B<stderr> stream will
+indicate the cause of any problem.
+
+An exit value of 2 indicates that perltidy ran to completion but there there
+are warning messages in the B<stderr> stream related to parameter errors or
+conflicts and/or warning messages in the B<errorfile> stream relating to
+possible syntax errors in the source code being tidied.