<http://schema.org/description>
"Did you know that if Google cannot crawl your robots.txt file, that it will stop crawling your whole site?This doesn't mean you need to have a robots.txt file, you can simply not have one.  But if you"^^<http://www.w3.org/2001/XMLSchema#string>
<https://www.seroundtable.com/google-crawl-robots-txt-17906.html>