<http://schema.org/description>
"After Joanna Shields announced at LeWeb that Facebook would deliver a new social plugin for websites that would allow Facebook users to subscribe to user updates on websites, the company ..."^^<http://www.w3.org/2001/XMLSchema#string>
<http://thenextweb.com/facebook/2011/12/08/facebook-rolls-out-its-new-subscribe-button-for-websites/>