Since we've never detailed the specifics of implementing the protocol, today we're releasing detailed documentation on how REP directives will be handled by the three major search providers.

• Common Robots.txt Directives such as

1. DIRECTIVE	IMPACT	USE CASE(s)
   Disallow	Tells a crawler not to crawl your site or parts of your site -- your site's robots.txt still needs to be crawled to find this directive, but the disallowed pages will not be crawled.	'No crawl' pages from a site. This directive in the default syntax prevents specific path(s) of a site from crawling.
   Allow	Tells a crawler the specific pages on your site you want indexed so you can use this in combination with Disallow. If both Disallow and Allow clauses apply to a URL, the most specific rule - the longest rule - applies.	This is useful in particular in conjunction with Disallow clauses, where a large section of a site is disallowed, except a small section within it.
   $ Wildcard Support	Tells a crawler to match everything from the end of a URL -- large number of directories without specifying specific pages.	'No Crawl' files with specific patterns, for eg., files with certain filetypes that always have a certain extension, say pdf; etc.
   Sitemap Location	Tells a crawler where it can find your sitemaps.	Point to other locations where feeds exist to point the crawlers to the site's content

   
   
   • Meta Tag Directives - such as
     
   
   

   DIRECTIVE	IMPACT	USE CASE(s)
   NOINDEX META Tag	Tells a crawler not to index a given page.	Don't index the page. This allows pages that are crawled to be kept out of the index.
   NOFOLLOW META Tag	Tells a crawler not to follow a link to other content on a given page.	Prevent publicly writeable areas from being abused by spammers looking for link credit. By NOFOLLOW, you let the robot know that you are discounting all outgoing links from this page.
   NOSNIPPET META Tag	Tells a crawler not to display snippets in the search results for a given page.	Present no abstract for the page on search results.
   NOARCHIVE META Tag	Tells a search engine not to show a "cached" link for a given page.	Do not make a copy of the page available to users from the search engine cache.
   NOODP META Tag	Tells a crawler not to use a title and snippet from the Open Directory Project for a given page.	Do not use the ODP (Open Directory Project) title and abstract for this page in Search.

   
   
   • Yahoo Specific Directives - such as Crawl-Delay: Allows a site to delay the frequency with which a crawler checks for new content
     
     NOYDIR META Tag: This is similar to the NOODP META Tag above but applies to the Yahoo! Directory, instead of the Open Directory Project
     
     Robots-nocontent Tag: Allows you to identify the main content of your page so that our crawler targets the right pages on your site for specific search queries by marking out non content parts of your page. We won't use the sections tagged as such for indexing the page or for the abstract in the search results.

Labels: Robots Exclusion Protocol REP, yahoo