gentoo-overlay/media-video/orion/metadata.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE pkgmetadata SYSTEM "http://www.gentoo.org/dtd/metadata.dtd">
<pkgmetadata>
	<maintainer type="person">
		<email>voyageur@gentoo.org</email>
		<name>Bernard Cafarelli</name>
	</maintainer>
	<use>
		<flag name="mpv">Use the <pkg>media-video/mpv</pkg> player (upstream default) instead of the <pkg>dev-qt/qtmultimedia</pkg> one</flag>
	</use>
</pkgmetadata>