I have problem in XSD. Let me explain in detail. Let us say I have XML with two nodes

If you observe that <node1> and <node2> have the same values. I want write the XSD in which i need to insist upon that two nodes i,.e node1 and node2 should have the same value.
It would be very helpful for me if some one help me.
Regards & thanks,
Nirmala Vijaya sekhar Varre