>
> I think part of the problem might be that any non-trivial schema is
> likely to be much wider than deep.
Indeed. Formatting a tree from left to right is much easier than top-to-bottom, because (a) the natural order of pre-order tree traversal corresponds to the (top-to-bottom, left-to-right) order in which we normally generate print output, and (b) in terms of usability, vertical scrolling of a very long document is generally more acceptable than horizontal scrolling of a very wide one.
To do this well you really need something like Graphviz that has algorithms to optimize placement of graph nodes on a two-dimensional page.
Michael Kay
Saxonica
