The simplest usage of a DTD involves actually adding the DTD into the prolog portion of your XML document, just after the XML processing instruction.

The skeleton (not quite valid) of a DTD looks something like the following:

     <?xml version = "1.0" encoding="UTF-8" standalone = "yes"?>
     <!DOCTYPE ROOT_ELEMENT_NAME [
	ELEMENT_DEFINITIONS_GO_HERE
	]>
     BODY_GOES_HERE.......

In this case we declare a document with a root element called ROOT_ELEMENT_NAME. For example, we might use the following syntax for our CONTACTS document

     <?xml version = "1.0" encoding="UTF-8" standalone = "yes"?>
     <!DOCTYPE CONTACTS [
	ELEMENT_DEFINITIONS_GO_HERE
	]>
     BODY_GOES_HERE.......