That could surely be expressed more clearly, but they don't actually contradict one another. %! is provided by Errno, but you don't need to C<use> it: Errno is automatically loaded when %! is seen: eirik@greencat[01:02:27]~$ perl -E 'say for keys %INC' feature.pm eirik@greencat[01:02:57]~$ perl -E 'say for keys %INC; say tied(%!)' Exporter.pm strict.pm Errno.pm feature.pm Errno=HASH(0x987ff8) eirik@greencat[01:02:58]~$ perl -E 'say for keys %INC; say tied(%!) if 0' Exporter.pm strict.pm Errno.pm feature.pm eirik@greencat[01:03:00]~$ --- via perlbug: queue: perl5 status: open https://rt.perl.org:443/rt3/Ticket/Display.html?id=119359Thread Next