Section 6.8. Supporting Document Automation


6.8. Supporting Document Automation

Two additional header tags have the primary functions of supporting document automation and interacting with the web server itself and with document-generation tools.

6.8.1. The <meta> Header Element

Given the rich set of header tags for defining a document and its relationship with others that go unused by most authors, you'd think we'd all be satisfied. But no, there's always someone with special needs. These authors want to be able to give even more information about their precious documentsinformation that browsers, readers of the source, or document-indexing tools might use. The <meta> tag is for those of you who need to go beyond the beyond.

<meta>

Function

Supplies additional information about a document

Attributes

charset , content , dir , http_equiv , lang , name , scheme

End tag

None in HTML; </meta> or <meta ... /> in XHTML

Contains

Nothing

Used in

head_content



The <meta> tag belongs in the document header and has no content. Instead, attributes of the tag define name/value pairs that associate the document. In certain cases, the web server serving the document uses these values to further define the document content type to the browser.

6.8.1.1. The name attribute

The name attribute supplies the name of the name/value pair defined by the <meta> tag. Neither the HTML nor the XHTML standard specifies any predefined <meta> names . In general, you are free to use any name that makes sense to you and other readers of your source document.

One commonly used name is keywords , which defines a set of keywords for the document. When encountered by any of the popular search engines on the Web, these keywords may be used to categorize the document. If you want your documents to be indexed by a search engine, consider putting this kind of tag in the <head> of each document:

 <meta name="keywords" content="kumquats, cooking, peeling, eating"> 

If the name attribute is not provided, the name of the name/value pair is taken from the http-equiv attribute.

6.8.1.2. The content attribute

The content attribute provides the value of the name/value pair. It can be any valid string ( enclosed in quotes if it contains spaces). It should always be specified in conjunction with either a name or an http-equiv attribute.

As an example, you might place the author's name in a document with:

 <meta name="Authors" content="Chuck Musciano & Bill Kennedy"> 

6.8.1.3. The http-equiv attribute

The http-equiv attribute supplies a name for the name/value pair and instructs the server to include the name/value pair in the MIME document header that is passed to the browser before sending the actual document.

When a server sends a document to a browser, it first sends a number of name/value pairs. While some servers might send a number of these pairs, all servers send at least one:

 content-type: text/html 

This tells the browser to expect to receive an HTML document.

When you use the <meta> tag with the http-equiv attribute, the server will add your name/value pairs to the content header it sends to the browser. For example, adding:

 <meta http-equiv="charset" content="iso-8859-1"> <meta http-equiv="expires" content="31 Dec 99"> 

causes the header sent to the browser to contain:

 content-type: text/html charset: iso-8859-1 expires: 31 Dec 99 

Of course, adding these additional header fields makes sense only if your browser accepts the fields and uses them in some appropriate manner.

6.8.1.4. The charset attribute

Internet Explorer versions 5 and earlier provided explicit support for a charset attribute in the <meta> tag. Set the value of the attribute to the name of the character set to be used for the document. This is not the recommended way to define a document's character set. Rather, we recommend always using the http-equiv and content attributes to define the character set.

6.8.1.5. The scheme attribute

This attribute specifies the scheme to be used to interpret the property's value. This scheme should be defined within the profile specified by the profile attribute of the <head> tag. [<head>, 3.7.1]

6.8.2. The <nextid> Header Element (Archaic)

This tag is not defined in the HTML 4 and XHTML standards and should not be used. We describe it here for historical reasons.

<nextid>

Function

Defines the next valid document entity identifier

Attributes

n

End tag

None

Contains

Nothing

Used in

head_content



The idea behind the <nextid> tag is to provide some way of automatically indexing fragment identifiers.

6.8.2.1. The n attribute

The n attribute specifies the name of the next generated fragment identifier. It is typically an alphabetic string followed by a two-digit number. A typical <nextid> tag might look like this:

 <html> <head> <nextid n=DOC54> </head> ... 

An automatic document generator might use the nextid information to successively name fragment identifiers DOC54 , DOC55 , and so forth, within this document.



HTML & XHTML(c) The definitive guide
Data Networks: Routing, Security, and Performance Optimization
ISBN: 596527322
EAN: 2147483647
Year: 2004
Pages: 189
Authors: Tony Kenyon

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