gentoo-overlay/dev-libs/xml-security-c/metadata.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE pkgmetadata SYSTEM "http://www.gentoo.org/dtd/metadata.dtd">
<pkgmetadata>
	<herd>cpp</herd>
	<use>
		<flag name='xalan'>Enable support for XSLT and XPath parsing 
			by <pkg>dev-libs/xalan-c</pkg></flag>
		<flag name='nss'>Use <pkg>dev-libs/nss</pkg> for certain crypto
			operations (configureable at runtime)</flag>
	</use>
</pkgmetadata>