gentoo-overlay/gnome-base/gnome-light/metadata.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE pkgmetadata SYSTEM "http://www.gentoo.org/dtd/metadata.dtd">
<pkgmetadata>
<maintainer type="project">
	<email>gnome@gentoo.org</email>
	<name>Gentoo GNOME Desktop</name>
</maintainer>
<use>
	<flag name="gnome-shell">Install <pkg>gnome-base/gnome-shell</pkg> and
		<pkg>x11-wm/mutter</pkg> for the standard GNOME 3 desktop mode</flag>
</use>
</pkgmetadata>