Help needed: the object oriented structure of dia

["Kautilya Jain" <kautilya cse iitb ac in>]

Dear dia developers,
 I'm Kautilya Jain, an UG student in the department of Computer Science &
Technology at Indian Institute of Tehnology, Bombay, India. I'm enrolled
in a course related to object oriented design and techniques. One of the
requirements of the course expects me to study the class/object structure
of the "dia" (or a similar tool, for this purpose I've selected dia). Can
you please help me in this regard, as in to re-direct me to the relevant
resources for this, or may be you can e-mail me the documents if they are
available with you. I'd be grateful to you for any help you provide me
for this.

Thanking you very much,
Regards,
Kautilya Jain.