sys-libs/timezone-data/metadata.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE pkgmetadata SYSTEM "http://www.gentoo.org/dtd/metadata.dtd">
<pkgmetadata>
  <herd>toolchain</herd>
  <maintainer>
    <email>djc@gentoo.org</email>
    <name>Dirkjan Ochtman</name>
  </maintainer>
  <use>
    <flag name='right_timezone'>
      Install the set of "right" timezones; these timezones include leap seconds
      when counting seconds since the epoch (while posix does not)
    </flag>
  </use>
</pkgmetadata>