How do I find out ALL bind variables available for the Staged Dunning Letter in R12?

How do I find out ALL bind variables available for Staged
Dunning Letter in R12 ? Where I can find this info? I assume some of them are
used in a sample of standard Oracle Staged Dunning Letter -
:ACCOUNT_ID,:CUSTOMER_SITE_USED_ID,:DUNNING_ID,:DELINQUENCY_ID,:LOCATION_ID,:PARTY_ID;
:RESOURCE_ID but I need :dunning_level and :customer_id that used in 11i to
find out the rate_interest. Would like to know if these are available as well. They are used to calc interest_rate in Dunning Letter in 11i (standard Oracle Report ARDLP.rdf) - trying to do the same way since interest rate is still stored in hz_cust_profile_amts in R12 seems like.