gentoo-overlay/gnome-base/gnome-session/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="gconf">Optional support for <pkg>gnome-base/gconf</pkg>
		configuration storage system</flag>
</use>
</pkgmetadata>