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Re: What are Semantics? (Was: Serving generic XML)

From: Kynn Bartlett <kynn@idyllmtn.com>
Date: Mon, 19 Aug 2002 13:29:08 -0700
Message-Id: <a05101001b98702a76c40@[10.0.1.5]>
To: Svgdeveloper@aol.com, www-tag@w3.org, www-style@w3.org

>So, according to Kynn, generic XML has no semantics.

It doesn't.

>Interestingly, he views a stylesheet as supplying semantics.

No, it doesn't, and no, I don't believe it does this.  Other people have
claimed that a random XML tag plus styles are equal to a header, but I
don't make this claim at all.

>Yet he claims that XHTML possesses "semantics".

It's got something which says "this is what this tag means", which
allows a diversity of UA methods to choose the right way to display
a given element.

>But what are the characteristics of such "semantics"? Are these 
>presentational pseudo-semantics only?

No, they define what an element means.  <h1> means "a header."  It's
up to the UA to display that accordingly.

If you make an arbitrary XML document, you cannot expect a browser to
determine that <headline> is supposed to be "a header" -- even if you
have visual presentation added on (via styles) which show that.

>Other views appear to assume that there is "semantic markup" - 
>presumably XML - which is "rich" in "semantics" and presentational 
>markup. Interpreted in some ways a view that is diametrically 
>opposed to Kynn's since he suggests that generic XML has "no" 
>semantics.

You can certainly build an XML markup language which contains semantics.
But arbitrary XML lacks it entirely; semantics only exist if all parts
of the equation (author, UA, etc) "know" what is "meant" by an element.

>Just as I was about to post this email, a post from Elliotte 
>provided a scale on which XML had the "most" in terms of semantics.

Well, Elliotte seems to be quite new to the idea of XML for some
reason, which makes you wonder just how big his nutshells are.  I read
his post, and for some reason he is ranking _all_ XML as "MOST", which
only holds true if the UA has knowledge of the XML document's meaning.
Without that, you're talking about arbitrary XML WITH NO UA KNOWLEDGE
OF THE SPECIFIC MARKUP LANGUAGE -- and of course, that's what we have
been talking about all along.

>It seems to me that we need to be clearer about terminology since 
>two, seemingly intelligent, individuals interpret the semantic 
>richness and poverty of XML in two diametrically opposed ways.
>Andrew Watt

Terminology is pretty simple.  Semantics equals "meaning."

If I write something in an arbitrary XML language, why yes, I can
have intimate knowledge of what it means.  <singer>Madonna</singer>
is indeed very sensible _TO ME_, the author.  I decide that it is
very semantically rich.

However, once I send it out to someone else, unless you have the
Rosetta stone to interpret what it means, it's just markup around
text.  It is no longer semantically rich, unless I make the
fundamental XML error of assuming that I can infer appropriate
meanings from the element names.  Which isn't how XML works, and
anyone telling you that it's the case really needs to take a step
back and figure this whole thing out.

And it is certainly not a solution to tell people with disabilities
that they should read source code in order to discern the meaning
of Web content.

LESS-THAN SINGER GREATER-THAN MADONNA LESS-THAN SLASH SINGER
GREATER-THAN -- I mean, what the heck?

You could probably construct something vaguely like IE's structured
view of unstyled XML -- the open and close plus/minus thing -- but
even then you are not conveying meaning, just structure.  The user
is able to "guess" at the structure if they're lucky, but I can't
see anyone seriously proposing that the Web needs to consist of
randomly named nested trees?

--Kynn

-- 
Kynn Bartlett <kynn@idyllmtn.com>                 http://kynn.com
Chief Technologist, Idyll Mountain            http://idyllmtn.com
Next Book: Teach Yourself CSS in 24       http://cssin24hours.com
Kynn on Web Accessibility ->>          http://kynn.com/+sitepoint
Received on Monday, 19 August 2002 16:29:21 GMT

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