<?xml  version="1.0"?>
<!-- validity constraint check for Production 56(Negative test)-->
<!DOCTYPE test
 [
 <!ELEMENT test ANY>
 <!ELEMENT landscape EMPTY>
 <!ENTITY image1 SYSTEM "d:\testspec\images\sunset.gif" NDATA gif>
 <!ENTITY image2 SYSTEM "d:\testspec\images\frontpag.gif" NDATA gif>
 <!ATTLIST landscape sun ENTITIES #IMPLIED>
]>
<test>
<landscape sun = "image3 image4"></landscape>
In an attribute declaration, values of type ENTITIES match the Name production and the ENTITIES value
does not match one or more names of entities declared in the DTD. 
</test>