gentoo-overlay/gnome-base/gdm/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="consolekit">Allow proper handling of removable media according
		to who is actually present on the machine.</flag>
	<flag name="dmx">Enables Distributed Multihead X (DMX) support</flag>
	<flag name="fallback">Install <pkg>x11-wm/metacity</pkg> as fallback in
		case gnome-shell greeter fails to start</flag>
	<flag name="fprint">Enables experimental fingerprint authentication using
		<pkg>sys-auth/fprintd</pkg></flag>
	<flag name="gnome-shell">Enables a greeter based on GNOME Shell (uses
		OpenGL)</flag>
	<flag name="introspection">Use <pkg>dev-libs/gobject-introspection</pkg>
		for introspection</flag>
	<flag name="remote">Enables support for secure remote connections</flag>
	<flag name="smartcard">Enables experimental smartcard authentication</flag>
	<flag name="xklavier">Use <pkg>x11-libs/libxklavier</pkg> for keyboard
		management</flag>
</use>
</pkgmetadata>