Re: Groups with non-zero intersections

Kevin Lindsey wrote:
> 
> Hi Jason,
> 
> > The problem is how to highlight routes on a road network, given that
> > multiple routes may have zero or more roads in common.
> 
> SVG does not allow an element to belong to disjoint groups.  

Its important to distinguish between the strictly hierarchical structure
as expressed in the xml source (and the SVG g element) on the one hand,
and the notion of set membership on the other hand. Set membership is
expressed by the class attribute, whose value is a space separated list
of set memberships.

> You will have
> to solve this one by manipulating your document's DOM.

Agreed; in this case, the CSS object model to alter the styling. Adding
a rule to the runtime stylesheet that makes all elements in a particular
set have a defined style is the easiest way to achieve this.

-- 
Chris