Advanced XML Schema Training Class?

One of my former clients has asked me to recommend an Advanced XML
Schema training class for them, and I couldn't think of any in the US.
 I know that there are a bunch of indie consultants that could easily
whip together a class, but does anyone know of a training company that
offers more then just a basic intro to XML Schema?  The client wants
to send one person to a training company, and not bring someone in for
a custom training class.

Don