Re: Tables and Charts

Chris Tilbury (C.J.Tilbury@estate.warwick.ac.uk)
Fri, 7 Jul 1995 16:55:12 BST


From: "Chris Tilbury" <C.J.Tilbury@estate.warwick.ac.uk>
To: bsittler@prism.nmt.edu (Benjamin C. W. Sittler), www-html@www10.w3.org
Date:          Fri, 7 Jul 1995 16:55:12 BST
Subject:       Re: Tables and Charts
Message-Id: <44E61C76A9@forest.estate.warwick.ac.uk>

On  7 Jul 95 at 9:31, Benjamin C. W. Sittler wrote:

> But doesn't CLASS have enforced values in the case of the <NOTE>
> element? Unless I misunderstand (this from [1]), NOTE has some
> predefined CLASSes with suggested renderings, i.e. WARNING, NOTE,
> and CAUTION.
> 
> [1] http://www.ing.unipi.it/Html/html3_ietf_draft/notes.html

The pertinent text is:

CLASS 
      This a space separated list of SGML NAME tokens and is used to
      subclass tag names. By convention, the class names are interpreted
      hierarchically, with the most general class on the left and the most
      specific on the right, where classes are separated by a period. The
      CLASS attribute is most commonly used to attach a different style to
      some element, but it is recommended that where practical class
      names should be picked on the basis of the element's semantics, as
      this will permit other uses, such as restricting search through
      documents by matching on element class names. Apart from the
      values suggested above, the conventions for choosing class names
      are outside the scope of this specification. 

So, no, they are not enforced. They (WARNING, CAUTION and NOTE) 
are "suggested values", and as indicated, the means by which other 
values are chosen are outside the scope of the specification. Most of 
the element tags have this caveat at the end of the CLASS attribute 
description. I wouldn't be suprised to eventually see something along 
these lines being made possible by the stylesheets specification, for NOTE

NOTE.warning : image.src = some_url
NOTE.warning : image.glyph = predefined_glyph_image

To allow the exact image which is displayed to be suggested by the 
document author.

Also bear in mind, that the mechanism by which the stylesheets allow 
you to identify individual instances of elements is by using the CLASS 
attribute. So, if you wanted CLASS="2dpie" to represent a 2D Pie chart, 
I could certainly set certain style options for /all/ the <TABLE 
CLASS="2dpie"> in a given document, but if I wanted to have, say, one 2d pie 
chart with red, green and yellow sections, and in the same document, 
another 2d pie chart, with blue, orange, mauve and yellow sections 
and to have the third segment "exploded", I couldn't (unless the 
colour and other information was fudged into the markup, which is 
precisely what we've been trying to avoid!)


Ciao,


Chris
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