""=Googlebot: No specific instructions (default)
"noarchive"=Googlebot: noarchive - does not allow Google to display cached content
"nosnippet"=Googlebot: nosnippet - does not allow Google to display excerpted or cached content
"noindex"=Googlebot: noindex - similar to the robots meta element
"nofollow"=Googlebot: nofollow - does not allow Google to pass any PageRank or link popularity to the link served
"noarchive"=Googlebot: noarchive - Google is not allowed to place this page in the cache memory