gentoo-overlay/app-doc/tldp-howto/metadata.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE pkgmetadata SYSTEM "http://www.gentoo.org/dtd/metadata.dtd">
<pkgmetadata>
	<herd>app-doc</herd>
	<use>
		<flag name='html'>Install the docs in multipage HTML format (default)</flag>
		<flag name='htmlsingle'>Install the docs in single page HTML format</flag>
		<flag name='pdf'>Install the docs in pdf format</flag>
		<flag name='text'>Install the docs in plain text format</flag>
	</use>
</pkgmetadata>