- From: Lachlan Hunt <lhunt07@netscape.net>
- Date: Sat, 06 Dec 2003 23:03:14 +1100
- To: jkorpela@cs.tut.fi
- Cc: www-html@w3.org
jkorpela@cs.tut.fi wrote:
>...there's an overall idea behind it, and the wording reflects this: some
>elements are regarded as "block elements", and this _basically_ reflects
>the idea of rendering an element as a rectangular box (which occupies the
>entire available width by default). It's fundamentally a presentational
>idea that has been converted into a _formally_ structural principle, in
>the sense of writing syntax rules accordingly.
>
I have to disagree with this idea that a block element is
fundamentally presentational. For an element to be a block, then it
must be able to make some sense as its own section and not necessarily
within another section (I'll cover that later). By section, which is
not to be confused with the <section> element, I mean that it is a
logical grouping of content.
A paragraph is a section of text, which can contain various elements
such as *emphasis*
new lines
abbreviations, lines of <code>, and various others that are grouped
together, hopefully, in a way that is meaningful.
Just because, visually, paragraphs, and other block elements, are
ususally rendered as a "rectangular box (which occupies the entire
available width by default)", does not mean that there is no logical
seperation between block elements.
For example, If I were to combine the two previous paragraphs into one,
like the following:
(Two paragraphs from above combined with no logical seperation of sections)
"A paragraph is a section of text, which can contain various elements
such as *emphasis* new lines abbreviations, lines of <code>, and various
others that are grouped together, hopefully, in a way that is
meaningful. Just because, visually, paragraphs, and other block
elements, are ususally rendered as a "rectangular box (which occupies
the entire available width by default)", does not mean that there is no
logical seperation between block elements."
Then although the basic meaning can still be understood by reading the
whole thing, no logical seperation between them or semantic meaning to
any section can be percieved.
It is this that leads to the confusion of a block element being
presentational, whereas presentation as a rectangular block of text, is
just the way in which we (those of us who are not visually impaired)
perceive the structure of a document. Of course, those of you who are
visually impared may percieve the structure in other ways. eg. aurally
by, perhaps, a longer pause between paragraphs, and other sections.
As humans, we need this kind of seperation to be able to logically
understand documents which, of course, is presentational, however this
does not change the fact that these sections need to be logically
seperated within the markup.
>...has the "good" old <b> element got semantics? Many
>people say it doesn't, and make this the crucial difference between <b>
>and <strong>. But I would say that <b> has the very exact semantics of
>specifying bold face font. It's purely presentational semantics, but
>that's a different issue.
>
What? Presentational Semantics? That's just combing two completely
seperate issues into one that does not make sense. Presentation is used
to convey the semantic meaning to humans, semantics do not convey
presentation. When someone reads something in bold, it suggests the
semantics of being important enough to be stongly empahsised, which is
why <b> has no real semantics, but <strong> does.
<snip/>
>It's so easy to think that some visual effects _are_ semantical (or structural), instead of being just some possible ways to expressing semantics (or structure).
>
If I understand you correctly, I think that's is kind of what I was
saying above.
>*) Besides, the presentational description of the distinction is purely
>visual. What is a rectangular box in speech, or in Braille?
>
This is why block elements cannot be purely presentational.
Rectangular boxes cannot be shown to a visually impaired person, however
sections can be through, as I said before, longer pauses aurally, or
larger gaps between brail symbols or whatever. The point is. the
semantic structure of a block, or section, can be conveyed in many
ways. Visually, as a rectangular box is just one.
>Well, yes, in a sense. And the distinction between <ol> and <ul> is
>essentially presentational. In both cases, the idea surely is that the
>list items are in a specific order. The distinction is that for <ol>, the
>order is made more explicit. A genuinely structural (i.e., not purely
>syntactic) list concept could, for example, contain markup that indicates
>that the items are in a priority order, or in time order, or in a random
>order.
>
The distinction between <ol> an <ul> is not just presentational. For
example the following lists only really make semantic sense as an
unordered list, or ordered list respectively:
<p>When I go shopping, I need to buy
<ul>
<li>Bread</li>
<li>Milk</li>
<li>Cheese</li>
</ul>
</p>
(This could, admittidly, also be ordered, however it doesn't really
matter whether bread is bought before milk or not)
<p>When washing your hair
<ol>
<li>Lather with shampoo</li>
<li>Rinse</li>
<li>Repeat as needed</li>
</ol>
</p>
(In this one, an <ul> would be inappropriate because, presumeably, you
should rinse before lathering.)
Of course, these can be presented in may different ways, yet still
retain the same semantics.
The <ul> example could be rendered like either of these two:
----
When I go shopping, I need to buy Bread, Milk and Cheese.
When I go shopping, I need to buy:
* Bread
* Milk
* Cheese
----
And the <ol> could be rendered in similar ways that also show the
necessity of the order.
----
When Washing your hair, first Lather with Shampoo, then Rinse and then
Repeat as needed
When washing your hair:
1. Lather with Shampoo
2. Rinse
3. Repeat as needed
----
The point is, that the distiction between ordered and unordered lists
is not just a presentational one. Presentation is simply the way in
which we, as humans, percieve the structure.
Received on Saturday, 6 December 2003 07:03:49 UTC