Which tables do I query to find the x_event_num_reversed value required by the pa_billing_pub.insert

Which tables do I query to find the x_event_num_reversed value required by the pa_billing_pub.insert_event API call when performing Revenue Adjustments at the project and task levels?  (This is the original event number which is to be credited by the adjusting entry.)

 

Here is the code I am currently trying to use:

 

FOR rev_num_rec IN

                       

                        -- Find the Event Number:

                        (SELECT  pdra.draft_revenue_num_credited

                        FROM    pa_draft_revenues_all pdra,

                                pa_cust_event_rdl_all pcera

                        WHERE   pdra.project_id = pcera.project_id

                        AND     pdra.draft_revenue_num = pcera.draft_revenue_num