Nice comparison! And yeah, why not add Boulder by Lincoln Stein.

Update: Boulder is a data format used internally in CGI.pm's query persistence. Here's an excerpt from perldoc CGI.

=head2 SAVING THE STATE OF THE SCRIPT TO A FILE:

    $query->save(FILEHANDLE)

This will write the current state of the form to the provided
filehandle.  You can read it back in by providing a filehandle
to the new() method.  Note that the filehandle can be a file, a pipe,
or whatever!



The file format used for save/restore is identical to that used by the
Whitehead Genome Center's data exchange format "Boulderio", and can be
manipulated and even databased using Boulderio utilities.  See

  http://stein.cshl.org/boulder/

for further details.
[download]

--
Tatsuhiko Miyagawa
miyagawa@cpan.org