HyperText Transfer format

This is a draft for internal discussion. TBD means "To be defined".
Comments please to timbl@vxcern.cern.ch. This copy was printed from the
source on   .

Introduction

This document defines the text mark-up format used for network transfer
of hypertext infoirmation. The ASCII (ISO-XXXX) character set [ref]  is
used, without extension.The format is marked up in SGML style, with
control information being introduced by a less than sign  "<", followed
by an alphanumeric "tag".  Following the tag, a number of attributes may
be specified, of the form

 	  attribute_name   =   value  

where the attribute name is alphanumeric, and the value is any printable
string not containing spaces.

Control information is terminated by a closing greater than ">" sign.

We refer to this mark up language as HyperText Markup Language, or HTML.

Default text

Unless otherwise defined by tags, text is transmitted as a stream of
lines. The division of the stream of characters into lines is arbitrary,
and only made in order to allow the text to be passed through systems
which can only handle text with a limited line length. The recommended
line length for transmission is 80 characters. The division into lines
has no significance (except in the case of the XMP and PLAINTEXT tags -
see below).

The names of tags and attributes are not case sensitive: they may be in
lower, upper, or mixed case with exactly the same meaning.  (In this
document they are gemerally represented in upper case.)

Tags

It is recommended that a parser ignores those tags which it does not
recognize. A list of tags currently defined follows:

<TITLE> ... </TITLE>

The text between the opening <TITLE> amd the closing </TITLE> is a title
for the hypertext node. Theer should only be one title in any node.

<A> ... </A>

The text between the opening <A> and the closing </A> is senstive text.
If the reader selects this text,  he should be presented with another
document whose network address is defined by the HREF attribute in the
<A> tag. The format of the network address is specified below.

An attribute REL may give the relationship described by the hyerptext
link.  Valid relationships are given below. The deafult relationship if
none other is given is SEE_ALSO.

An attribute ID may give an alphanumeric identifier used to reference
the anchor from other anchors. See the section on addressing below.

Relationship values

SEE_ALSO
INCLUDES	PART_OF
EMBED	EMBEDDED_IN

TBD...

<NODE NAME=xx ENABLE=xxx>
<AVAILABLE>

TBD

<LINK>

This is similar to <ANCHOR> but the link has no specific anchor within
the document.  It may have an ID, in which case any reference to it is
effectively  to the anchor it references.

<DATE>

TBD

<PLAINTEXT>

This tag indicates that all following text is to be taken litterally, up
to the end of the file.  Plain text is designed to be represented in the
same way as example <XMP> text, with fixed width character and
significant line breaks.

This tag allows the rest of a file to be read efficiently without
parsing. Its presence is an optimisation.

<XMP> ..</XMP>

The text between these tags is to be portrayed in a fixed width font, so
that any formatting done by character spacing on successive lines will
be maintained.  Between these tags, line boundaries are significant,
and are to be interpreted as a move to the start of a new line.
 
Between thse tags, the ASCII Horizontal Tab (HT) character should be
interpreted as the smallest positive nonzero number of spaces which will
leave the number of characters so far on the line as a multiple of 8.
Its use is not recommended however.

<P>

This tag indicates a new paragraph. The exact representation of this
(indentation,  leading, etc) is not dfined here, and may be a function
of other tags.

<H1>, <H2>, <H3>
<HP1>, <HP2>
<DL>, <DD>, <DT>
<UL>, <OL>, <LI>

These tags are kept as defined in the CERN SGML guide [ref]. Their
definition is completely historical.