<?xml  version="1.0"?>
<!-- validity constraint check for Production 56(Negative Test)-->
<!DOCTYPE test
 [
 <!ELEMENT test ANY>
 <!ELEMENT id1 EMPTY>
 <!ELEMENT id2 EMPTY>
 <!ELEMENT idrefs EMPTY>
 <!ATTLIST id1 UniqueName ID #REQUIRED>
 <!ATTLIST id2 UName ID #IMPLIED>
 <!ATTLIST idrefs reference IDREFS #IMPLIED>
 ]>
<test>
<id1 UniqueName = "AC456"></id1>
<id2 UName = "BC567"></id2>
<idrefs reference = "AC456 #567"></idrefs>
Negative test for validity constraint of IDREFS.
In an attribute decl, values of type IDREFS does not match the name production
</test>