html-spec/Intro.html at master · dckc/html-spec · GitHub

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<!DOCTYPE HTML PUBLIC "-//W3O//DTD WWW HTML 2.0//EN">
<HTML>

<HEAD>
<TITLE>Hypertext Markup language and SGML</TITLE> <NEXTID
N="z2"></HEAD>

<BODY>

<H1>HTML and SGML</H1>

<P>This section describes the relationship between HTML and SGML,
and guides the newcomer through interpretation of the <A
NAME="z1" HREF="DTDHeading.html">DTD</A>.
(This is not a full tutorial on SGML, and in the event of any
apparent conflict, the SGML standard is definitive.)

<P>The HyperText Markup Language is an application conforming
to International Standard ISO 8879 -- Standard Generalized Markup
Language [<A NAME="z0" HREF="References.html#z3"> SGML</A> ].
SGML is a system for defining structured document types,
and markup languages to represent instances of those document
types.

<P>Every SGML document has three parts:

<UL>

<LI>An SGML declaration, which binds SGML processing quantities
and syntax token names to specific values.
For example, the SGML declaration in the HTML DTD specifies that
the string that opens an end tag is <CODE>&#60;/</CODE> and the
maximum length of a name is 72 characters.

<LI>A prologue including one or more document type declarations,
which specifiy the element types, element relationships and attributes,
and references that can be represented by markup.
The HTML DTD specifies, for example, that the HEAD element contains
at most one TITLE element.

<LI>An instance, which contains the data and markup of the document.
</UL>

<P>We use the term HTML to mean both the document type and the
markup language for representing instances of that document type.

<P>The SGML declaration for HTML is given in the appendix ``SGML
Delcaration for HTML.'' It is implicit among WWW implementations.<!-- @@ include an explanation of how to use sgmls with this stuff -->

<P>The prologue for an HTML document should look like:<!-- @@ explain more -->

<PRE>
      &#60;!DOCTYPE HTML PUBLIC "-//W3O//DTD W3 HTML 2.0//EN"&#62;

</PRE>

<H3>NOTE: Missing <CODE>&#60;!DOCTYPE</CODE> declaration</H3>

<P><EM>Many extant HTML documents do not contain a prologue.
Implementations are encouraged to infer the above prologue if
the document does not begin with <CODE>&#60;!</CODE>.</EM>
</BODY>
</HTML>