c:\WorkingFolder>perl -e "$/ = 5; print qq{$/\n};  {local $/; print qq{$/\n}; $/ = 2; print qq{$/\n};} print $/"

__END__
Output is:
5        #initally set $/ to something we can see when we print it
         #2nd print, proves localsised $/ is set to undef
2        #localised copy of $/ set to 2
5        #inner scope where $/ was localised has ended. Original $/ is reinstated by Perl