The Error Style tells InterFormNG what to do if a problem should occur.
The list of monitored errors can be seen here:
For each possible problem 4 settings are possible:
Unset
This is undecided. Use whatever value that may have been selected earlier.
Ignore
Ignore the problem and proceed.
Warning
Issue a warning in the log, but continue processing the file.
Fatal
Stop processing the input file and issue a/an (fatal) error.