Alternative tags in element?

Hi,

  I've just started working with XML Schema, so please forgive me if the answer to 
my question is obvious. 

  I want to create an element, say "Foo" that contains a sequence of elements which 
have different tags, say "Bar" and "Glob".  So these would be legal:

   <Foo><Glob/><Bar/></Foo>

  <Foo><Bar/><Glob/></Foo>

  <Foo><Bar/><Glob/><Bar/></Foo>

In the complexType for Foo elements, can you specify that it contains a sequence 
of alternative elements, in arbitrary order?  Or do I have to create a wrapper element 
for the alternatives and place them in a union?

Any help welcome ...

-- Paul
--
Paul Steckler
National ICT Australia
paul DOT steckler AT nicta.com.au