Uses for the META Element
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Client Pull
Support Key: [IE2|M2|N1.1|O3.2]
Description
This use of the META element causes a document to be automatically loaded after a specified number of seconds. This form uses the HTTP-EQUIV attribute as the identifier in the META statement with a value of "Refresh". The CONTENT attribute can be either an integer value [N] representing the number of seconds to wait before refreshing the current page, or a combination value separated by a semi-colon representing a time value [N] and a URL page destination [URL].
Syntax 1: <meta http-equiv="Refresh" content="[N]" />
Syntax 2: <meta http-equiv="Refresh" content="[N]; URL=[URL]" />
Example:
<meta http-equiv="Refresh" content="5; URL=http://www.foo.com/foo.html" />
Editor Identification
Support Key: NA
Description
The "Generator" value for the NAME attribute is very commonly inserted into documents by HTML editor programs. It specifies as a value the name of the editor that generated the code. Web browsers ignore this META element usage.
Syntax: <meta name="Generator" content="[Editor Name]" />
Example:
<meta name="Generator" content="Editor Brand X" />
Search Engine Identification
Support Key: NA
Description
There are two commonly used META element syntaxes for helping in the indexing of web documents in popular search engines. The "Keywords" value for the NAME attribute is a comma separated list of keywords relating to the current document, while the "Description" value for the NAME attribute represents the current document description summary. Web browsers ignore this META element usage but some search engine robots use it to help index files.
Syntax 1: <meta name="Keywords" content="[Search Engine Keywords]" />
Syntax 2: <meta name="Description" content="[Search Engine Description]" />
Example 1:
<meta name="Description" content= "Index DOT Html is a complete reference to HTML" />
Example 2:
<meta name="Keywords" content="HTML,history,hypertext,tags,reference" />
Document Character Set Identification
Support Key: [IE?|M?|N?|O?]
Description
HTTP allows the MIME type and character set/encoding to be specified as an HTTP-header. Using a "Content-Type" value for the HTTP-EQUIV attribute allows the same capability in HTML. Of greatest interest to authors will be the ability to define the document's character set. HTTP 1.1 requires the "charset" value to be honored, but also states that some older HTTP 1.0 clients will not understand it. See "RFC 1700: Assigned Numbers" - Sec: Character Sets and RFC 2045: Multipurpose Internet Mail Extensions - Sec: 2.2 for more information.
Syntax: <meta http-equiv="Content-Type" content="[MIME Type]; charset=[Charset String]" />
Example:
<meta http-equiv="Content-Type" content="text/html; charset=Shift-JIS" />
"Pragma" Browser Cache Override
Support Key: [IE?|M?|N?|O?]
Description
The "Pragma" value for the HTTP-EQUIV attribute specifies caching behavior. Several values are possible for this HTTP-header, but the value of most use to authors will be "no-cache." When this is used as the value for the CONTENT attribute, the document may not be cached (well, SHOULD not be...) by a caching system anywhere along the connection chain between the browser and the source document. A browser emits the same Pragma HTTP header to a document's source location when a user requests the document to be reloaded. HTTP 1.1 replaces "Pragma: no-cache" with "Cache-Control: no-cache", but understands "Pragma" as well. For more information on caching, take a look at http://www.mnot.net/cache_docs/.
Syntax: <meta http-equiv="Pragma" content="no-cache" />
Example:
<meta http-equiv="Pragma" content="no-cache" />
"Expires" Browser Cache Override
Support Key: [IE?|M?|N?|O?]
Description
The "Expires" value for the HTTP-EQUIV attribute gives as its CONTENT value a date [Date Value]. The Expiration value is used to indicate to a browser when time-sensitive information becomes old. Browsers must not cache the requested page beyond the date given. The presence of an EXPIRES field does not imply that the original resource WILL change or cease to exist at, before, or after the time indicated, but does speak to the expected timeliness of the material. Setting the CONTENT attribute to a date in the past, or even to an illegal value of "0" tells the browser to always look for a new version of the page. For more information on caching, take a look at http://www.mnot.net/cache_docs/.
Syntax: <meta http-equiv="Expires" content="[Date Value]" />
Example:
<meta http-equiv="Expires" content="Mon, 01 Jan 1996 23:59:59 GMT" />
PICS Identification
Support Key: [IE3|M|N|O]
Description
The Platform for Internet Content Selection (PICS) is a system designed to associate categorizing labels with document content. The system originated as a method to help control access to questionable content, but can also be used to label and classify other types of document content as well, such as code signing, privacy, and intellectual property rights management.
Syntax
Can vary quite a bit. Usually created by going to a site and filling out a form. See http://www.w3.org/PICS/Overview.html and http://vancouver-webpages.com/PICS/HOWTO.html for more details.
Inter-page Transition Filter Effects
Support Key: [IE4|M|N|O]
Description
This is a special syntax only allowed by Internet Explorer 4.0 and above to allow special effects to occur while the page is loading or unloading. This syntax uses the same 'filter' CSS property syntax that IE also supports.
Syntax: <meta http-equiv="[Event]" content="Duration=[Duration],Transition=[Transition Type]" />
    [Event] is one of: Page-Enter, Page-Exit, Site-Enter, or Site-Exit
    [Duration] is a floating point value specifying the transition time in seconds.milliseconds
    [Transition Type] is an integer from 0 to 23 representing a transition effect (consult links below.)
Example:
<meta http-equiv="Page-Exit" content="RevealTrans(Duration=2.500,Transition=6)" />
[Note: For more information on Transition Filter types, consult the references at Index DOT Css and Microsoft]

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