This is Perl module Array::Diff. INSTALLATION Array::Diff installation is straightforward. If your CPAN shell is set up, you should just be able to do % cpan Array::Diff Download it, unpack it, then build it as per the usual: % perl Makefile.PL % make && make test Then install it: % make install DOCUMENTATION Array::Diff documentation is available as in POD. So you can do: % perldoc Array::Diff to read the documentation online with your favorite pager. Daisuke Murase