implementing a custom interface

I have three types in my XSD: Savings, Checking, Certificate.

Is it possible to add something (to the .xsdconfig?) that makes all
three types implement an interface I created?

I want my beans to be like this:

Product
	getStaringBal()
	getEndingBal()

Savings implements Product
	getSavingsSpecificStuff()

Checking implements Product
	getCheckingSpecificStuff()

make sense?

Jason
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