<?xml  version="1.0"?>
<!-- validity constraint check for Production 56(Negative Test)-->
<!DOCTYPE tokenizer
 [
 <!ELEMENT tokenizer ANY>
 <!ELEMENT a EMPTY>
 <!ATTLIST a first ID #REQUIRED>
 <!ATTLIST a second ID #REQUIRED>
 ]>
<tokenizer>
<a first = "AC1999" second="BC1999"></a>
This is a Negative validity test for ID.
There is more than attribute of type ID for the element a

</tokenizer>