gentoo-overlay/app-emulation/virtualbox-bin/metadata.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE pkgmetadata SYSTEM "http://www.gentoo.org/dtd/metadata.dtd">
<pkgmetadata>
	<!-- maintainer-needed -->
	<use>
		<flag name="additions">Install Guest System Tools ISO</flag>
		<flag name="chm">Install kchmviewer binary to enable online help (in MS CHM format)</flag>
		<flag name="headless">Install without any graphic frontend</flag>
		<flag name="sdk">Enable building of SDK</flag>
		<flag name="vboxwebsrv">Install the VirtualBox webservice</flag>
		<flag name="rdesktop-vrdp">Install the rdesktop client integration</flag>
	</use>
</pkgmetadata>