Hi All! Just to close this and perhaps some one is interested. I have now had several excellent feedbacks from the IBExpert Support forum which solved the problem. The relevant part has to be like this:
select rdb$set_context('USER_TRANSACTION', 'bulkload', '1') from rdb$database into :somevar; update files f set f.ccy_total_claim_amount_net = :TCACCY, f.ccy2_total_claim_amount_net = :TCACCY2, f.date_filter = :DATEFILTER where f.file_id = :FILE_ID; So the presence of the transaction property in the variable does the trick. Kind regards Christian P.S.: I still think that this is also helpful in a normal block statement within one db.