<http://schema.org/about>
"The transition from June to July will be delayed by circumstances beyond everyone's control. Time will stand still for one second on the evening of Saturday, Ju"^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.mnn.com/green-tech/research-innovations/stories/leap-second-will-make-time-stand-still-this-weekend>