<?xml  version="1.0"?>
<!-- validity constraint check for Production 56(Positive Test)-->
<!DOCTYPE tokenizer
 [
 <!ELEMENT tokenizer ANY>
 <!ATTLIST tokenizer UniqueName ID #REQUIRED>
 ]>
<tokenizer UniqueName = "AC1999">
This is a positive test for validity constraints
Giving a unique name to the attribute ID an ID Attribute default as #required
</tokenizer>