gentoo-overlay/sys-fs/squashfs-tools/metadata.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE pkgmetadata SYSTEM "http://www.gentoo.org/dtd/metadata.dtd">
<pkgmetadata>
	<herd>livecd</herd>
	<use>
		<flag name="xz">Enable support for XZ ("LZMA2") compression using <pkg>app-arch/xz-utils</pkg></flag>
	</use>
</pkgmetadata>