Yahoo ROBOT from http://help.yahoo.com/help/us/ysearch/basics/basics-10.html
If you run a web site and do not want your content to be accessible through the cache, you can use the NOARCHIVE meta-tag. Place this in the section of your documents:
< META NAME="ROBOTS" CONTENT="NOARCHIVE" >
This tag will tell robots not to archive the page. Our crawler will continue to index and follow links from the page, but it will not display a cached page in search results.
Please note that the change will occur the next time the search engine crawls the page containing the NOARCHIVE tag (typically at least once per month).
Also, the NOARCHIVE tag controls only whether the cached page is shown. To prevent the page content from being indexed, use the NOINDEX tag. To prevent the crawler from following links, use the NOFOLLOW tag.