XS: Construction Rule Features

[Paul Prescod <papresco@xxxxxxxxxxxxxxxxxxxxxxxxx>]

James suggests a CLASS feature a la CSS/HTML:

"Support for element type subclassing

CSS1 allows the CLASS attribute to be conveniently used for sub-classing
element types. Obviously DSSSL cannot attach
any special meaning to a particular attribute, but it could allow a
style sheet to declare a particular attribute as working like
CLASS in HTML, and then provide some way for referring to the class in
an element construction rule. For example, 

(declare-class-syntax "CLASS" "!")

(element P!WARNING  (make paragraph (literal "Warning: ")
(process-children)))"

I don't use a "CLASS-style" element in most of my DTDs although I know
many DTDs have them. I *do* want to do different things based on
attributes, though. So I would prefer a more general way to have
attributes in the "query" for an element construction rule. 
An element construction rule with an attribute specified could be more
specific than any without. Two rules with two different attributes
specified would be of the same level and would be an error.

Also, there is a common idiom in CSS stylesheets where one construction
rule applies to many different GIs:

H1, H2, H3, H4, H5{
  font-family: Times New Roman,serif;
  font-weight: 500;
  font-style: normal;
  font-size: 10pt;
  color: #000000;
}

Could we do this too:

(element H1 H2 H3 H4 H5 
	(make paragraph 
		(font-size: (calculate-size (GI)) ))

 Paul Prescod


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