Requirement is a Database for Aircraft Parts Distributors and Orders.
A. The Business process :-
A.1 Customers submit Request For Quotations, (RFQs) online, and they are provided with Quotations.
A.2 Customers can prepare an Order based on the the quotation.
A.3 There is only Vendor source for these Customers.

B. Things of Interest :-
B.1 Aircraft Parts
B.2 Customers
B.3 Orders
B.4 Quotations

C. How are they related ?
C.1 Customer can be associated with zero, one or many Quotations.
C.2 Customer can be associated with zero, one or many Orders.
C.3 An Order can be associated with zero, one or many Quotations.
C.4 A Quotation can be associated with zero, one or many Orders.