XSD: Allow elements from different namespace anywhere in a sequence

Question

I\'ve been trying out the following. I want to create an XSD for an XML where certain elements are allowed to appear only once and need to be valid, and elements from other

Answer 1

In XSD 1.1 you can do this very easily by defining an open content model:

  
    
  
  ... regular content model ...

There's no easy way to do it in 1.0; you just have to put an optional wildcard in every possible position.