HTTP headers may be generated by CGI scripts, and in Apache and CERN httpd by using a side file containing metadata. Other servers may have other mechanisms to generate headers. Note that certain server-generated headers may not be overridden (such as Date), and that others are only meaningful with a non-200 status code. Using an HTTP header is preferable to using META tags, since the header will be understood by cache agents and proxies in addition to browsers, and metadata (such as PICS data) may be associated with image files, sound files, etc.
| Tag | Source | Description |
|---|---|---|
| Expires | HTTP/1.0 | Expiry date of document |
| Content-type | HTTP/1.0 | Content type and character set of document |
| Content-language | HTTP/1.0 | Natural Language of document |
| Refresh | Netscape | Delay till browser reloads (optional URL) |
| PICS-Label | PICS | Document content labelling |
| Cache-Control | HTTP/1.1 | Control of document cacheing |
| Vary | HTTP/1.1 | Alternate forms available |
The date and time after which the document should be considered expired. Controls cacheing in HTTP/1.0. In Netscape Navigator, a request for a document whose expires time has passed will generate a new network request (the copy in local cache will be discarded). B
Web robots may delete expired documents from a search engine, or schedule a revisit.
Dates must be given in RFC850 format, in GMT. E.g. (META tag):
<META HTTP-EQUIV="expires" CONTENT="Wed, 26 Feb 1997 08:21:57 GMT">or (HTTP header):
Expires: Wed, 26 Feb 1997 08:21:57 GMTIn HTTP 1.0, an invalid value (such as "0") may be used to mean "immediately".
The HTTP content type may be extended to give the character set. As an HTTP/1.0 header, this unfortunately breaks older browsers. As a META tag, it causes Netscape Navigator to load the appropriate charset before displaying the page. E.g.
<META HTTP-EQUIV="Content-type" CONTENT="text/html; charset=ISO-2022-JP">
May be used to declare the natural language of the document. May be used by robots to categorize by language. The corresponding Accept-Language header (sent by a browser) causes a server to select an appropriate natural language document. E.g.
<META HTTP-EQUIV="Content-language" CONTENT="en-GB">or (HTTP header)
Content-language: en-GBlanguages are specified as the pair (language-dialect); here, English-British
Specifies a delay in seconds before the browser automatically reloads the document. Optionally, specifies an alternative URL to load. E.g.
<META HTTP-EQUIV="Refresh" CONTENT="3;URL=http://www.some.org/some.html">or (HTTP header)
Refresh: 3;URL=http://www.some.org/some.htmlIn Netscape Navigator, has the same effect as clicking "Reload"; i.e. issues an HTTP GET with Pragma: no-cache (and If-Modified-Since header if a cached copy exists).
Defines the name of an alternate cache to Netscape Navigator. E.g.
<META HTTP-EQUIV="Ext-cache" CONTENT="name=/some/path/index.db; instructions=User Instructions">
Platform-Independant Content rating Scheme. Typically used to declare a document's rating in terms of adult content (sex, violence, etc.) although the scheme is very flexible and may be used for other purposes.
See also the PICS HOWTO.
Specifies the action of cache agents. Possible values:
Specifies that alternates are available. E.g.
<META HTTP-EQUIV="Vary" CONTENT="Content-language">or (HTTP header)
Vary: Content-languageimplies that if a header Accept-Language is sent an alternate form may be selected.
| Tag | Source | Description |
|---|---|---|
| Description | Spidering | Document description |
| Robots | Spidering | Web Robot control |
| Keywords | Search | Document indexing keywords |
| Generator | Publish | Document creation agent |
| Formatter | Publish | Document creation agent |
| Author | Publish | Document Author |
| Classification | Netscape | Classification |
| Copyright | Publish | Document copyright |
| VW96.ObjectType | mk-metas | Document Type |
| Rating | mk-metas | content rating |
| DC.TITLE | Dublin | Document Title |
| DC.CREATOR | Dublin | Author or Creator |
| DC.SUBJECT | Dublin | Subject and Keywords |
| DC.DESCRIPTION | Dublin | Description |
| DC.PUBLISHER | Dublin | Publisher |
| DC.CONTRIBUTORS | Dublin | Other Contributors |
| DC.DATE | Dublin | Date resource was made available in its present form. |
| DC.TYPE | Dublin | Resource Type |
| DC.FORMAT | Dublin | Data representation of the resource |
| DC.IDENTIFIER | Dublin | Resource Identifier |
| DC.SOURCE | Dublin | Work from which resource is derived |
| DC.LANGUAGE | Dublin | Language(s) of the intellectual content |
| DC.RELATION | Dublin | Relationship to other resources. |
| DC.COVERAGE | Dublin | Spatial and temporal coverage |
| DC.RIGHTS | Dublin | Link to rights-management statement. |
| htdig-keywords | HTdig | keywords |
| htdig-noindex | HTdig | noindex |
| htdig-email | HTdig | Recipient address |
| htdig-notification-date | HTdig | Notification date |
| htdig-email-subject | HTdig | email subject |
| Author-Corporate | Apple | Corporate Author |
| Publisher | Apple | Publisher |
| Publisher-Email | Apple | email address of publisher |
| Author-Personal | Apple | Author |
| Identifier-URL | Apple | URL |
| Identifier | Apple | Serial number |
| Bookmark | Apple | Bookmarkable URL |
| Coverage | Apple | name of applicable area |
| EKBU | Kodak | numeric |
| EKdocType | Kodak | Document Type |
| EKdocOwner | Kodak | numeric |
| EKdocTech | Kodak | numeric |
| EKreviewDate | Kodak | yyyymmdd |
| EKArea | Kodak | numeric |
| ABSTRACT | IBM | Page Abstract |
| CC | IBM | ? |
| ALIAS | IBM | Page URL |
| OWNER | IBM | Page owner (email) |
Controls Web robots on a per-page basis. E.g.
<META NAME="ROBOTS" CONTENT="NOINDEX,FOLLOW">Robots may traverse this page but not index it.
A short, plain language description of the document. Used by search engines to describe your document. Particularly important if your document has very little text, is a frameset, or has extensive scripts at the top. E.g.
<META NAME="description" CONTENT="Citrus fruit wholesaler.">
Keywords used by search engines to index your document in addition to words from the title and document body. Typically used for synonyms and alternates of title words. E.g.
<META NAME="keywords" CONTENT="oranges, lemons, limes">
Typically the unqualified author's name.
Typically the name and version number of a publishing tool used to create the page. Could be used by tool vendors to assess market penetration.
Undefined.
Typically an unqualified copyright statement. Limited value, since undefined format.
Simple content rating. Not widely used.
Based on an early version of the Dublin Core report, using a defined schema of document types such as FAQ, HOWTO. Not widely used.
Dublin Core Elements. See the Reference Description
HTdig tags. See the HTdig META page.
<LINK rel=help href="http://some.org/help.html">
| Tag | Source | Description |
|---|---|---|
| top | HTML3.2 | Top of hierarchy |
| contents | HTML3.2 | Table of Contents |
| index | HTML3.2 | Index of current document |
| glossary | HTML3.2 | Glossary for current document |
| copyright | HTML3.2 | Copyright Statement |
| next | HTML3.2 | Next document to visit |
| previous | ViewCall | Previous document in set |
| help | HTML3.2 | help for current document |
| search | HTML3.2 | Search page for current document |
| home | ViewCall | Default URL for Home key |
| bookmark | ViewCall | Default URL for Bookmark key |
| tickertape | ViewCall | URL of tickertape message |
| vmail | ViewCall | Define mailto gateway |
| ViewCall | ||
| ViewCall | ||
| ViewCall | ||
| ViewCall |
See HTML 3.2
>LINK rev=made href="mailto:document-owner">A hotkey in the Lynx browser will send mail to the document owner.
See HTML 3.2
<BASE href="http://vancouver-webpages.com/VWbot/metatags.detail.html">A BASE tag is useful if the document may be copied to another location, or accessed by another path with a symbolic link, imagemap redirect, etc.
See HTML 3.2
Any other META tags in use ?
Please let me know
Vancouver Webpages