Rubric is a Perl module is currently just a placeholder and a container for documentation. You don't want to actually use Rubric, even if you want to use Rubric.
Rubric is a note-keeping system that also serves as a bookmark manager. Users store entries, which are small (or large) notes with a set of categorizing "tags." Entries may also refer to URIs.
Rubric was inspired by the excellent http://del.icio.us/ service and the Notational Velocity note-taking software for Mac OS.