Business Domain Model Diagram vs. Class Diagram

[Daniel CarMichael]

Would somebody tell the difference between the Business Domain Model and Class Diagram?
I'm not sure BDM is showing the actual Class relationship. What does the line connecting two entities in the BDM means? Association relationship? If this is the case and noting that we're not allowed to alter the BDM, doesn't that mean that we can't add new relationship among the entities shown?
Actually I'm not going to alter the existing 'lines', just want to add new relationships which I think are missing in the Class Diagram. For example, say, if I create a new association between Segment and Seats, will this count as altering the BDM?

[Bagwan Mehrat]

Your discretion.
Do as you feel appropriate, and see how Sun grades it.

[Robin Zhang]

should we follow the bussines domain modle or change it?
[ July 01, 2002: Message edited by: Robin Zhang ]

[Vivek Viswanathan]

I have used the BDM, and I have added many new relations to it. I have also included other Business Object and related them to the existing Business Object. I have added this so that I can understand the system better, it would probally help the grader understand what I think of the system. I wont be supplying the BDM as a class diagram, my class diagram will contain additional information like Control , Entity and Boundary Classes etc. I dont think i will be specifying all the methods for all the class that I will be includng in my class diagram.

Vivek