<?xml version="1.0"?>
<!DOCTYPE student [
	<!ELEMENT student (#PCDATA)>
	<!ATTLIST student
		first CDATA #REQUIRED
		middle CDATA #IMPLIED
		last CDATA #IMPLIED > 
	<!ENTITY myfirst "Snow">
	<!ENTITY mymiddle "I">
	<!ENTITY mylast "Man">
]>

<!-- testing invalid attvalue -->
<student first="Snow<Man">My Name is SnowMan. </student>