Yahoo just rolling out again its search engine for another update on its algorithm and additional directive on its search according to their blog about adding tags and page level exclusion tag like NOINDEX, NOARCHIVE, NOSNIPPET, NOFOLLOW.

Previously, these page level tags could only be expressed within html pages through the META directive (for e.g. ), but based on feedback from our webmasters, Yahoo! now enables these tags to be expressed through X-Robots-Tag directive in the http header, giving webmasters the flexibility to achieve exclusions on PDF, Word documents, PowerPoint, video, and other file types, including html files, and increasing their coverage through a simplified process. Additionally, webmasters no longer need access to html templates in order to express exclusions for html files.

You just need to add this directive to the http header of you page.

X-Robots-Tag: NOINDEX — If you don’t want to show the URL in the Yahoo! Search results.

X-Robots-Tag: NOARCHIVE — If you don’t want to display cache link in the search results page.

X-Robots-Tag: NOSNIPPET — If you don’t want to display summary in the search results page.

X-Robots-Tag: NOFOLLOW — If you don’t want Yahoo! to crawl links in the page.

This changes is also being included in the changes being made by yahoo in the next few days reflecting the said addition and algorithm changes. Let us see how it will affect my sites into this changes.