Declaring the Attribute Entity

This leads us into our second step.  To reference the binary entity, an attribute of type entity must be declared.  The syntax is:

<!-- Note: the element does not have to be empty-->
<!ELEMENT element.name EMPTY>
	<!ATTLIST element.name
		 attribute.name ENTITY #REQUIRED|#IMPLIED>

Once the entity attribute is declared, it can reference any binary entity that is declared in the DTD.

Tip:	Only attributes can be used to reference a binary entity.  
	They cannot be expanded inside of a document like parsed 
	entities.