This page lists the allowed extension values for the name="" attribute of the <meta> element in HTML5. You may add your own values to this list, which makes them legal HTML5 metadata names. We ask that you try to avoid redundancy; if someone has already defined a name that does roughly what you want, please reuse it.
|Keyword||Brief description||Link to more details||Synonyms||Status|
|cache||Value must be "public", "private", or "no-cache",. Inteded as a simple way to tell user agents whether to store a copy of the document or not. An alternate for HTTP/1.1's cache-control; for publishers without access to modifying cache-control.
This doesn't actually work, use HTTP headers instead
|keywords||A comma separated list of keywords that describe this page. Not necessary these days; search engines use much more sophisticated means to determine the page's contents.||none||Unendorsed|
|robots||A comma separated list of operators explaining hos search engine crawlers should treat the content. Possible values are "noarchive" to prevent cached versions, "noindex" to prevent indexing, and "nofollow" works as the link rel value with the same name. This meta name is already supported by every popular search engine.||Robots exclusion protocol, Googlebot, Yahoo! Slurp, and Ask.com Teoma||Proposal|
For the "Status" section to be changed to "Accepted", the proposed keyword must have been through the Microformats process, and been approved by the Microformats community. If it fails to go through this process, it is "Unendorsed".
For more details, see the HTML5 specification.