Help referencing an attribute of Class

Hi,

I am implementing BAdi UDM_BASIS_RULE.

In the EVALUATE method, I need to have reference to the Business Partner number, but I don't know how to reference it.

There is a parameter (I_BUSINESS_PARTNER) which has a type ref to IF_UDM_BUPA_TRANSACTION_DATA.

And IF_UDM_BUPA_TRANSACTION_DATA has an attribute: PARTNER_ID which holds the value I would like to reference back in the EVALUATE method.

Can someone please tell me the syntax for accessing this field from the EVALUATE method.

Thanks very much,

Andy