head-elts.sgm

<h3>Title: TITLE

<p>Every HTML document must contain a <tag/TITLE/ element.

<p> The title should identify the contents of the document in a global
context.  A short title, such as "Introduction" may be meaningless out
of context. A title such as "Introduction to HTML Elements" is more
appropriate.
<NOTE>The length of a title is not limited; however, long titles may
be truncated in some applications. To minimize this possibility,
titles should be fewer than 64 characters.</note>

<p> A user agent may display the title of a document in a history list
or as a label for the window displaying the document. This differs
from headings (<hdref refid=headings>), which are typically displayed
within the body text flow.

<h3 id=base>Base Address: BASE

<p>The optional <tag/BASE/ element provides a base address for
interpreting relative URLs when the document is read out of context
(see <hdref refid=hyperlink>). The value of the <attr/HREF/ attribute
must be an absolute URI.

<h3>Keyword Index: ISINDEX

<p>The <tag/ISINDEX/ element indicates that the user agent should
allow the user to search an index by giving keywords. See <hdref
refid=query> for details.

<h3>Link: LINK

<p>The <tag/LINK/ element represents a hyperlink (see <hdref
refid=hyperlink>).  Any number of LINK elements may occur in the
<tag/HEAD/ element of an HTML document.  It has the same attributes as
the <tag/A/ element (see <hdref refid=a>).

<p>The <tag/LINK/ element is typically used to indicate authorship,
related indexes and glossaries, older or more recent versions,
document hierarchy, associated resources such as style sheets, etc.

<h3>Associated Meta-information: META

<p> The <tag/META/ element is an extensible container for use in
identifying specialized document meta-information. Meta-information
has two main functions:

<ul>
<li>to provide a means to discover that the data set exists and
how it might be obtained or accessed; and 

<li>to document the content, quality, and features of a data set,
indicating its fitness for use. 
</ul>

<p> Each <tag/META/ element specifies a name/value pair.  If multiple
META elements are provided with the same name, their combined
contents&mdash;concatenated as a comma-separated list&mdash;is the value
associated with that name.
<note>The <tag/META/ element should not be used where a specific
element, such as <tag/TITLE/, would be more appropriate. Rather
than a <tag/META/ element with a URI as the value of the <attr/CONTENT/
attribute, use a <tag/LINK/ element.
</note>

<p>HTTP servers may read the content of the document <tag/HEAD/ to
generate header fields corresponding to any elements defining a value
for the attribute <attr/HTTP-EQUIV/.
<note>The method by which the server extracts document meta-information is
unspecified and not mandatory. The <tag/META/ element
only provides an extensible mechanism for identifying and embedding
document meta-information &mdash; how it may be used is up to the individual
server implementation and the HTML user agent.
</note>

<p>Attributes of the META element:

<tl>
<tli>HTTP-EQUIV: binds the element to an HTTP header
field. An HTTP server may use this information to process the
document. In particular, it may include a header field in the
responses to requests for this document: the header name is
taken from the <attr/HTTP-EQUIV/ attribute value, and the header value
is taken from the value of the <attr/CONTENT/ attribute. HTTP header
names are not case sensitive.

<tli>NAME: specifies the name of the name/value pair. If not present,
<attr/HTTP-EQUIV/ gives the name.

<tli>CONTENT: specifies the value of the name/value pair.

</tl>

<p>Examples

<p>If the document contains:

<listing><![CDATA[
<META HTTP-EQUIV="Expires"
      CONTENT="Tue, 04 Dec 1993 21:29:02 GMT">
<meta http-equiv="Keywords" CONTENT="Fred">
<META HTTP-EQUIV="Reply-to"
      content="fielding@ics.uci.edu (Roy Fielding)">
<Meta Http-equiv="Keywords" CONTENT="Barney">
]]></listing>

<p>then the server may include the following header fields:

<listing><![CDATA[
Expires: Tue, 04 Dec 1993 21:29:02 GMT
Keywords: Fred, Barney
Reply-to: fielding@ics.uci.edu (Roy Fielding)
]]></listing>

<p>as part of the HTTP response to a <code/GET/ or <code/HEAD/ request
for that document.

<p>An HTTP server must not use the <tag/META/ element to form an HTTP
response header unless the <attr/HTTP-EQUIV/ attribute is present.

<p>An HTTP server may disregard any <tag/META/ elements that specify
information controlled by the HTTP server, for example <code/Server/,
<code/Date/, and <code/Last-modified/.

<h3>Next Id: NEXTID

<p> The <tag/NEXTID/ element is included for historical reasons only.
HTML documents should not contain <tag/NEXTID/ elements.

<p> The <tag/NEXTID/ element gives a hint for the name to use for a
new <tag/A/ element when editing an HTML document. It should be
distinct from all <attr/NAME/ attribute values on <tag/A/
elements. For example:

<listing><![CDATA[
<NEXTID N=Z27>
]]></listing>