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<start> <ref name="e2"/> </start> <define name="e2"> <element name="e2"> <element name="e3"> <text/> </element> </element> </define>
</grammar>
<grammar xmlns=“relaxng.org/ns/structure/1.0”>
<start> <ref name="e2"/> </start> <define name="e2"> <element name="e2"> <element name="e3"> <text/> </element> </element> </define>
</grammar>