How do you add an attribute to an element

[Segull]

Hi there,
Let's say we have a DTD simmilar to the following format
<!DOCTYPE BOOK [
<!ELEMENT BOOK (TITLE,(CHAPTER)+)>
<!ELEMENT CHAPTER (TITLE,AUTHOR))>
<!ELEMENT TITLE %TEXT >

<!ENTITY TEXT (#CDATA)>
]>
Now if we wanted to add an attribute for example <ISBN> (which is a REQUIRED attribute) to the <TITLE> element only under the <BOOK> element without changing the other elements.. could anyone suggest me a method of doing this

ps: you cannot just change the element name "TITLE" of the book

 

[JontyMC]

<!ATTLIST BOOK ISBN CDATA #REQUIRED>

http://www.w3schools.com/dtd/dtd_examples.asp