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6.8 Supporting Document Automation
There
are two additional header tags that have the primary functions of
supporting document automation and interacting with the web server
itself and 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 documents information that
might be used by browsers, readers of the source, or
document-indexing tools. 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 |
header and has no content. Instead, attributes of the tag define
name/value pairs that associate the document. In certain cases, these
values are used by the web server serving the document 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 are 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
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 provides 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. [Section 3.7.1]
6.8.2 The <nextid> Header Element (Archaic)
This tag is not defined in the HTML 4 or
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 |
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.
