gentoo-overlay/app-misc/tracker/metadata.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE pkgmetadata SYSTEM "http://www.gentoo.org/dtd/metadata.dtd">
<pkgmetadata>
<herd>gnome</herd>
<use>
  <flag name="cue">Enable cue sheet parsing</flag>
  <!-- 'firefox-bookmarks' instead of 'firefox' to prevent most users from
	   enabling this by accident; it has some stability problems and
	   performance implications -->
  <flag name="firefox-bookmarks">Install bookmark data miner plugin for
    <pkg>www-client/firefox</pkg> and <pkg>www-client/firefox-bin</pkg></flag>
  <flag name="gsf">Enable <pkg>gnome-extra/libgsf</pkg> based data extractor and
  for ODT.</flag>
  <flag name="iptc">Enable extraction of IPTC data from pictures</flag>
  <flag name="iso">Enable extraction of metadata from ISO disk images</flag>
  <flag name="laptop">Make tracker power management aware</flag>
  <flag name="libsecret">Enable libsecret support to store login
  credentials</flag>
  <flag name="miner-fs">Enable tracker-miner-fs (required for filesystem indexing)</flag>
  <flag name="nautilus">Enable tracker to integrate with
    <pkg>gnome-base/nautilus</pkg> by providing entries in its context menu
  </flag>
  <flag name="playlist">Add support for playlists</flag>
  <flag name="thunderbird">Install email data miner plugin for
    <pkg>mail-client/thunderbird</pkg> and
	<pkg>mail-client/thunderbird-bin</pkg></flag>
  <flag name="xps">Add support for XPS file format through <pkg>app-text/libgxps</pkg>.</flag>
</use>
</pkgmetadata>