Thanks Limbic. I did not know that there was a list there, too. perllexwarn was the only list for 'use warnings' that I could find.

waswas-fng in my case I have a hash of values that comes from XML::Simple. If a given tag does not have a parameter e.g.<foo>blah</foo> vs. <foo bar="x">blah</foo> the value for $xml->{bar} is undefined.

--traveler