help in processing compositor's in XML Schema?

I am trying to define the following in a XML Schema. I would like the
elements , header1, header2, and header3 to be un-ordered within themselves
and child1 and child2 to be un-undered within themselves. but I would like
to define that the header's occur before the child's. 

Without introducing more tags, Is there a way to do this ??

	<parent>
		<header1/>
		<header2/>
		<header3/>
		<child1/>
		<child2/>
	</parent>


Bill Riegel
Landmark Graphics
Phone: 713-839-3388