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Re: Inconsistancy...

From: Ian Jacobs <ij@w3.org>
Date: Mon, 08 Feb 1999 18:20:04 -0500
Message-ID: <36BF7124.9DA60BEF@w3.org>
To: KOSSICK PAUL J CIV SA-ALC/LP <PAUL.KOSSICK@lpgate1.kelly.af.mil>
CC: www-html-editor@w3.org
KOSSICK PAUL J CIV SA-ALC/LP wrote:
> 
> Sirs,
>         I'm trying to resolve an inconsistancy in the proposed standard for
> HTML 4.0 cited below, and hope you can help.
>         The problem comes from the statements concerning white space around
> comment delimiters.  First, the statements seem only to refer to white
> space, and neglect to specify whether any other sort of data (printable
> characters, etc.) are permitted.  Further, there is no elaboration on WHY
> white space is forbidden between the markup declaration open delimiter and
> the comment delimiter, yet permitted for the close delimiters.  Is there
> some reason for these restrictions?

Hello Paul,

This is an SGML issue as it concerns how comments are defined in SGML.
All defintive answers to your questions may be found (I trust) in
the SGML standard. The part of the spec that you are reading is
an informative reference to the SGML definition of comments
(since HTML is an SGML application). 

There's a chance that we got our informative description
wrong, and I apologize if we did. However, it is beyond
the scope of my knowledge of SGML to tell you why
white space is forbidden in some cases (if indeed it is forbidden).

Thus, for definitive answers, please consult the SGML standard.

>         Finally, in the next section, an example clearly shows text and
> white space (the ELEMENT declaration and associated values) between the
> declaration and comment delimiters.  And still I can't think of a reason you
> may WANT white space between the closing comment delimiters and the close
> declaration delimiters.

Nor can I.

>         Is this the final specification for this standard? 

What version are you looking at? The latest
version is available from the W3C technical
reports page: http://www.w3.org/TR

> Am I just  reading the text wrong?  To be frank, I've found most of the text very
> confusing and tedious,

I'm sorry to hear that. Tedious may be unavoidable, since this
is not "HTML for Dummies" and our goal was to define
a standard, not to entertain. 

Confusing is unfortunate, although some of the topics are not for the
faint
of heart. Can you indicate any places in particular? Please
note, for example, that the SGML tutorial was included as
a *bare minimum* description of what one would need to be able
to recognize in the DTD. It is not crucial to the correctness
of the normative parts of the HTML 4.0 specification.

> and I'm definitely not a tyro when it comes to
> telecom protocols and the Internet (I've been involved in the net since
> before CERN released their first browser (read 'User Agent'...can't you guys
> just say 'Web Client' like we used to?)).

In my opinion, both terms are quite nondescript. It takes more
than two words to explain the concept fully in any case.
Around W3C, I hear "user agent" a lot more than "Web client".

>         Just in case, NO, I haven't checked the errata sheet yet...my
> sincere apologies if this is already covered there, but if you could please
> respond to the general questions about clarity and the basis for some of the
> specs, I would appreciate it.  Thank you in advance.

Thank you for taking the time to comment,

 - Ian


> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 3.2.4 Comments
> 
> HTML comments have the following syntax:
> 
> <!-- this is a comment -->
> <!-- and so is this one,
>     which occupies more than one line -->
> 
> White space is not permitted between the markup declaration open
> delimiter("<!") and the comment open delimiter ("--"), but is permitted
> between the comment close delimiter ("--") and the markup declaration close
> delimiter (">"). A common error is to include a string of hyphens ("---")
> within a comment. Authors should avoid putting two or more adjacent hyphens
> inside comments.
> 
> Information that appears between comments has no special meaning (e.g.,
> character references are not interpreted as such).
> 
> 3.3 How to read the HTML DTD
> 
> Each element and attribute declaration in this specification is accompanied
> by its document type definition fragment. We have chosen to include the DTD
> fragments in the specification rather than seek a more approachable, but
> longer and less precise means of describing an element's properties. The
> following tutorial should allow readers unfamiliar with SGML to read the DTD
> and understand the technical details of the HTML specification.
> 
> 3.3.1 DTD Comments
> 
> In DTDs, comments may spread over one or more lines. In the DTD, comments
> are delimited by a pair of "--" marks, e.g.
> 
> <!ELEMENT PARAM - O EMPTY       -- named property value -->
> 
> Here, the comment "named property value" explains the use of the PARAM
> element type. Comments in the DTD are informative only.
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

-- 
Ian Jacobs (jacobs@w3.org) 
http://www.w3.org/People/Jacobs
Received on Monday, 8 February 1999 18:21:43 GMT

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