Fast Formula to get department and Business Unit of a candidate offer letter

Summary:

We need to write a fast formula to get department and Business Unit of a candidate offer letter, as we need to send a specific email notification to be sent to only those candidates which are in example in Department 101 and Business Unit XYZ, by adding this Fast Formula a criteria in our Candidate selection Process Flow. I searched through the DBI list and only see the DBI as "IRC_JOB_OFFER_LRG_OBJ_OFFER_ID" and did not found any direct DBI for Department and Business Unit.

Does anyone know what is the DBI item for Offer letter - Department and Business Unit. Or, if someone could help with a sample fast formula.