Re: HTML 3.2 PR

Harold A. Driscoll (harold@driscoll.chi.il.us)
Fri, 15 Nov 1996 20:46:25 -0600


Message-Id: <2.2.32.19961116024625.00638ae4@pop.interaccess.com>
Date: Fri, 15 Nov 1996 20:46:25 -0600
To: "Carl Morris" <msftrncs@htcnet.com>
From: "Harold A. Driscoll" <harold@driscoll.chi.il.us>
Subject: Re: HTML 3.2 PR
Cc: <marc@ckm.ucsf.edu>, "WWW HTML List" <www-html@w3.org>

At 19:01 15/11/96 -0600, Carl Morris wrote:
>I am going to pick on people with this:
>
><! is a comment in HTML >

While you'd apparently like to consider anything beginning with a <! a
comment, the HTML specification [1] takes a very different view of the
matter. [quoted below]

><! -- this is a comment in SGML -- >
>
>Why?  An HTML parser has no business trying to figure out SGML, an SGML
>parser being used on an HTML document on the other hand may have use
>for the declaration.  It needs to be described this way.  

Quite to the contrary. Since HTML is (by definition, see RFC 1866 in the
Abstract) an application of SGML, SGML parsers are quite appropriate HTML
parsers.

>Calling <! > not an HTML comment is misleading to those people who have 
>no use for SGML.

Actually, calling <! a comment open symbol is what is misleading, since it
is incorrect.

Please, to keep this discussion on track, it would be very helpful to cite
references for facts, and to clearly identify opinions which differ from the
facts as such.

The notation used for SGML comments, and that used for SGML DOCTYPEs, might
certainly seem "weird" to some folks unfamiliar with them. But, like many
conventions (both social and technical) in life, a degree of  consistency
and predictability is more important (more valuable) than occasional
shortening of notation.

In both the cases (comments and DOCTYPE) there are strong benefits from
following established conventions [2] which far outweigh the casual
disadvantages.

/Harold

[1] RFC 1866 PS T. Berners-Lee, D. Connolly, "Hypertext Markup Language -
2.0", 11/03/1995. (Pages=77) (Format=.txt)
http://ds.internic.net/rfc/rfc1866.txt

3.2.5. Comments

   To include comments in an HTML document, use a comment declaration. A
   comment declaration consists of `<!' followed by zero or more
   comments followed by `>'. Each comment starts with `--' and includes
   all text up to and including the next occurrence of `--'. In a
   comment declaration, white space is allowed after each comment, but
   not before the first comment.  The entire comment declaration is
   ignored.

      NOTE - Some historical HTML implementations incorrectly consider
      any `>' character to be the termination of a comment.

   For example:

    <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
    <HEAD>
    <TITLE>HTML Comment Example</TITLE>
    <!-- Id: html-sgml.sgm,v 1.5 1995/05/26 21:29:50 connolly Exp  -->
    <!-- another -- -- comment -->
    <!>
    </HEAD>
    <BODY>
    <p> <!- not a comment, just regular old data characters ->

[2] Consider the historical case of distinguishing between the number zero
and the letter O. For many years, engineers have used a slash through the
number 0. This convention was implemented in a number of hardware devices,
including various IBM printers during the mainframe era. Apparently ignorant
of this convention, an minister turned computer programming book author
noted the confusion and introduced the convention of using a slash through
the letter O. As you can imagine, while each usage was rather arbitrary,
things got very confusing when programmers (using slash with letter O) got
their printouts (using slash with number 0).
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Harold A. Driscoll                       mailto:harold@driscoll.chi.il.us
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