November 3, 1997

DR. WEBSITE: Using META Tags For Identification and Control of Pages

By David Fiedler and Scott Clark

Dear Dr. Website®: I can't find any info on <META...>. Could you explain what parameters can be used with META tags, and specifically, how to have a page automatically launch to another page?

The META tags have many uses, among which are identifying who created a page, what specs it follows, the keywords for a page, and the description of a page. To answer your specific question, the Refresh parameter can be used to cause the page to reload, or to go to another page. Here is the complete list of META tags:

HTTP-EQUIV tags
Expires
Pragma
Content-Type
Content-Language
Refresh
Window-target
Ext-cache
Set-Cookie
PICS-Label
Cache-Control
Vary
Lotus
NAME attributes
Robots
Description
Keywords
Author
Generator
Formatter
Classification
Copyright
Rating
VW96.ObjectType
Dublin Core
HTML 4.0
HTdig
HTdig notification

Other NAME attributes are useful for specific in-house applications.

META tags should always be placed in the head of the HTML document between the HEAD tags, before the BODY tag. This is very important with framed pages, as a lot of developers tend to forget to include them on individual framed pages.

Expires: This tells the browser the date and time when the document will be considered "expired." If a user is using Netscape Navigator, a request for a document whose time has "expired" will initiate a new network request. An illegal Expires date, (such as "0"), is interpreted by the browser as "expires immediately." Dates must be given in the RFC850 format, with a GMT time zone:

<META HTTP-EQUIV="expires" CONTENT="Wed, 26 Feb 1997 08:21:57 
GMT">

Pragma: This is another way to control browser caching. To use this tag, the value must be "no-cache". When this is included in a document, this prevents Netscape Navigator from caching a page locally.

<META HTTP-EQUIV="Pragma" CONTENT="no-cache">

Refresh: This is what our reader is looking for. It specifies a delay in seconds before the Web browser reloads the document automatically. It can also specify an alternative URL for the browser to load, causing one page to switch to another (often used for a "forwarding address").

<META HTTP-EQUIV="Refresh" CONTENT="0;URL=http://www.refresh.com">

Remember to place quotation marks around the CONTENT attribute, or your page will be stuck in the mud.

Set-Cookie: This is yet another method of setting a cookie in the Web browser. If you use an expiration date, the cookie is considered permanent and will be saved to disk; otherwise, it will be considered valid only for the current session and will be erased upon closing the browser.

<META HTTP-EQUIV="Set-Cookie" 
CONTENT="cookievalue=xxx;
expires=Tuesday, 20-Oct-98 14:32:21 GMT; path=/">

Window-target: This one specifies the "named window" of the current page, and can be used to prevent a page from appearing inside another framed page.

<META HTTP-EQUIV="Window-target" CONTENT="_top">

For additional META information, visit Galactus' META info page, as well as the Vancouver META tag page.

Click here for Webdeveloper.com's home page

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Date: 19971103