<http://schema.org/description>
"AdSenseAdvisor notified publishers via a  WebmasterWorld thread that the competitive ad filter now supports up to 500 possible filters.  I believe this limit is up from 200 filtered URLs from 2006.  S"^^<http://www.w3.org/2001/XMLSchema#string>
<https://www.seroundtable.com/archives/019798.html>