gentoo-overlay/gnome-base/gnome-control-center/metadata.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE pkgmetadata SYSTEM "https://www.gentoo.org/dtd/metadata.dtd">
<pkgmetadata>
	<maintainer type="project">
		<email>gnome@gentoo.org</email>
		<name>Gentoo GNOME Desktop</name>
	</maintainer>
	<use>
		<flag name="flickr">Add support for using photos from flickr as desktop background</flag>
		<flag name="gnome-online-accounts">Enable configuration panel for <pkg>net-libs/gnome-online-accounts</pkg> accounts</flag>
		<flag name="ibus">Enable support for enhanced input methods through <pkg>app-i18n/ibus</pkg></flag>
	</use>
</pkgmetadata>