robots-exclusion: Difference between revisions
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== References == | == References == | ||
=== | === Normative === | ||
* [http://gmpg.org/xmdp/ | * [http://gmpg.org/xmdp/ XMDP] | ||
* [http://www.robotstxt.org/wc/meta-user.html The Robots META Tag] | * [http://www.robotstxt.org/wc/meta-user.html The Robots META Tag] | ||
=== Informative === | |||
* [http://www.robotstxt.org/wc/norobots.html A Standard for Robot Exclusion] | * [http://www.robotstxt.org/wc/norobots.html A Standard for Robot Exclusion] | ||
* [http://www.google.com/bot.html#noindextags Googlebot Frequently Asked Questions] | * [http://www.google.com/bot.html#noindextags Googlebot Frequently Asked Questions] | ||
Revision as of 01:51, 22 June 2005
Robot Exclusion Profile
Draft Specification 2005-06-18
Editors
- Peter Janes
- volunteers welcome
Concept
Copyright
Temporarily © 2004-2005 by the author. However, it is intended to submit this specification to a standards body with a liberal copyright/licensing policy such as the GMPG. See the GMPG Principles for more details. Anyone wishing to contribute to this effort MUST read those principles, especially those regarding copyright and licensing, and agree to them before contributing.
Patents
The author neither holds nor intends to apply for any patents on anything required to implement this specification.
Abstract
The Robot Exclusion Profile is a reworking of the Robots META tag (and less-standard extensions) as a microformat.
Introduction
The Robots META tag is used to provide page-specific direction for web crawlers. While being useful in many cases, its page-specific nature means it cannot be used to restrict crawlers from indexing only certain sections of a document. Several attempts have been made to create more granular solutions through various methods but have perceived shortcomings that limit their use; the Robots Exclusion Profile defines a microformat that can be applied to any element or set of elements in a page.
Like other microformats such as hcalendar, the Robot Exclusion Profile defines a set of class names that may be applied to (X)HTML elements. class can be applied to almost every (X)HTML element, which means that authors may be as specific or general as they wish in their application. This differs from the similarly-purposed rel="nofollow" attribute, which may only be applied to (and does not refer to the content of) a specific inline link. (It is interesting to note that this behaviour is entirely encompassed by the use of class="robots-nofollow" on the same element.) Classes are also additive, so multiple values can be specified at once, e.g. class="robots-nofollow robots-noindex". For robot exclusion in particular, this allows authors to specify multiple rules for an element without adding unnecessary extra markup.
Format
Profile URL
http://example.org/xmdp/robots-profile# (obviously preliminary)
XMDP Profile
robots-nofollow:: Informs robots that links contained by the element are not to be followed. robots-follow:: Informs robots that links contained by the element are to be followed. robots-noindex:: Informs robots that the content of the element is not to be included as part of the page. robots-index:: Informs robots that the content of the element is to be included as part of the page. robots-noarchive:: Informs caching robots that the content of the element is not to be included in their cached copy. robots-archive:: Informs caching robots that the content of the element is to be included in their cached copy.
Examples
Removing page content:
<head profile=”http://example.org/xmdp/robots-profile#”> ... <div class=”robots-noindex”>There once was a man from Nantucket…</div> <p>This page is not about <span class=”robots-noindex”>pornography</span>.</p>
Showing nofollow in conjunction with votelinks, and applying it in parallel with relnofollow:
<head profile=”http://example.org/xmdp/robots-profile#”>
...
<p class=”robots-nofollow”>This is <a href=”http://example.com/bogus”>a bogus link</a>
and so is <a href=”http://example.net/bogus”>this</a>.</p>
<p>I don't like <a rel="nofollow" rev="vote-against" class="robots-nofollow"
href="http://example.com/disagree">this page</a>
but I do like <a rev="vote-for" href="http://example.com/agree">this one</a>.</p>
Preventing images from being stored by search engines, forcing them to be retrieved from the originating website:
<head profile="http://example.org/xmdp/robots-profile#"> ... <p><img src="example.png" class="robots-noarchive" alt="Private image" /></p>
A more complex example is available which also shows how the robots metadata may be visualized.
References
Normative
Informative
- A Standard for Robot Exclusion
- Googlebot Frequently Asked Questions
- The ROBOTS META Tag
- RelNoFollow Draft Specification
- This page was contributed from the technorati developers' wiki.
Thanks
Issues
These are open issues that have been raised in various forums. The "efficacy" and "collateral damage" issues from rel="nofollow" also apply.
Precedence
- Should earlier values take precedence or later? Does
class="robots-nofollow robots-follow"means the same asclass="robots-nofollow"orclass="robots-follow"? metatag suggests not using conflicting or repeating directives and so does not specify precedence- Interaction with relnofollow: what does
class="robots-follow" rel="nofollow"mean?
Specificity
- Does not allow blocking of specific UAs à la A Standard for Robot Exclusion
Keywords
- The keywords
allandnoneare defined by the Robots META Tag as convenience shortcuts to enable or disable the combination ofnofollowandnoindex, but predate Google'snoarchiveand should not be considered to include it. As a result, for purposes of clarity and simplicity, they are not included in this version of the Robots Exclusion Profile.