RE: [XML Schema 1.1] I respectfully recommend these changes to <assert> and <alternative>

> 
> Wouldn't it be easier and better if the XPath was not 
> restricted and allowed us to factor in information, 
> regardless of where it is located in the tree?
> 

It's a conscious design decision that when you define what constitutes a
valid book, the definition should be context-independent: if it's a valid
book in one situation, then it remains valid in any other situation.

XSLT and XQuery rely on this context-independence - if a function returns a
valid book, or if you select a valid book by XPath navigation, then the
element can be used in any context that expects a valid book, without having
to be revalidated to ensure it's still valid in the new context.

Regards,

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