RE: XSD to ER Diagram

> I would recommend modelling your data first, then looking at 
> your document requirements together with your data model to 
> define your document structure.

Or to put it slightly differently:

(a) model the information

(b) decide what messages need to be transmitted to communicate subsets of
that information

(c) write XSD schemas to describe each of those messages.

Michael Kay
http://www.saxonica.com/