The style agenda
Subject: The style agenda
From: Bert Bos <email@example.com>
Date: Tue, 30 May 1995 21:15:40 +0200 (METDST)
X-Mailer: ELM [version 2.4 PL24]
Now that the style list is officially open, it is time to think about
its agenda. Style sheets are very much needed on the Web, so we should
be very careful that we don't make any mistakes, because we probably
can't fix them later.
My intuition says that Arena's style sheets are heading roughly in the
right direction, although a number of details will need to change. But
I'd rather not trust intuition.
So I suggest that we collect some arguments pro and con the following
issues, before we start with the details of syntax and the list of
style properties. Now that the mailings are archived (thanks, Nick!),
we can refer back to those arguments when the full proposal is
1. Are we sure there is no existing language that we can copy?
2. Do we agree on the goals as stated in the Cascading Style Draft
and the `Charter'?
For example: do the phrases "not SGML-complete" from the former
and "useful subset of all possible SGML" from the latter
contradict each other or not?
In particular, do we agree on the fifth goal in the `Charter',
which states that the style language does not depend on the
particular names of elements & attributes of HTML?
And, if we agree that a new language is needed:
3. What is the (abstract) formatting model that we assume?
For example: TeX uses `boxes & glue', DSSSL has a `page model &
flow ojects', the simple model that I described has a page
model with five areas each of which is filled with a continuous
stream of words. And how about non-visual media?
A relatively high-level model is dangerous ("doesn't it exclude
something important?") but useful, since it allows us to write
translators to lower-level languages such as TeX.
4. How powerful can/need we make the addressing scheme?
Although the difference is small, I think my proposal is more
elegant, more powerful, and not more complex then Håkon's.
5. How many levels of cascading priorities do we need?
As a computer scientist, I would say that Håkon's three is a
strange number, I would rather have either two or very
many. (I consider `default' and `lens' as outside this range,
since they need not use the same language.)
6. How powerful can/need we make the expression language?
We probably don't need things like macros right away, but
numerical and other operators might be useful.
And finally, we can invent a syntax (context-free, of course) and draw
up a list of style properties, being careful that we don't include
things that will make it impossible to add more powerful properties
I'm sure we will encounter difficult decisions along the way. I've
already started a collection, though I hope that they will turn out
to be not so difficult after all.
Bert Bos Alfa-informatica
<firstname.lastname@example.org> Rijksuniversiteit Groningen
<http://www.let.rug.nl/~bert/> Postbus 716, NL-9700 AS GRONINGEN