gentoo-overlay/media-fonts/mplus-outline-fonts/metadata.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE pkgmetadata SYSTEM "http://www.gentoo.org/dtd/metadata.dtd">
<pkgmetadata>
<herd>cjk</herd>
<herd>fonts</herd>
<use>
  <flag name='ipafont'>Generates new fonts merged with <pkg>media-fonts/ja-ipafonts</pkg></flag>
</use>
</pkgmetadata>