Oracle Grants is there a link between pa_expenditure_items_all and pa_cust_event_rdl_all

Not Projects but Grants, so no worries if this can't be picked up. Thought someone might know. When the Revenue Event gets created in Grants from a cost based award it agglomerates expenditure items if they're still eligible, but I can't obviously see any scientific way to link the results in pa_cust_event_rdl_all back to either pa_expenditure_items_all or gms_award_distributions. So I'm missing a table/link as it can't have been left floating. Anyone know what that is?