(since the Meiji era) eras can only be renewed when a new emperor
succeeds his predecessor. Until then new eras were proclaimed for
various reasons, including the succession of the shogunate during the
Tokugawa shogunate.
WWW: http://search.cpan.org/~dmaki/DateTime-Calendar-Japanese-Era-0.07/
PR: ports/113162
Submitted by: Masahiro Teramoto <markun at onohara.to>
