Specifically, we're extending our support of page level exclusion tags -- NOINDEX, NOARCHIVE, NOSNIPPET, NOFOLLOW -- to provide additional control for archiving and summarization of ANY file type. Previously, these page level tags could only be expressed within html pages through the META directive (for e.g. <META NAME="Slurp" CONTENT="NOARCHIVE">), 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.
Webmasters can use this control by adding it at page level tags to the X-Robots-Tag directive in the HTTP Header.