<http://schema.org/description>
"I am not sure if the title of this post is all that clear.  Basically, if you go to the Robots.txt informational page at the Wikipedia and scroll down to the  Directives within a page it claims Google"^^<http://www.w3.org/2001/XMLSchema#string>
<https://www.seroundtable.com/archives/005116.html>