Testing batch controls involves reviewing transmittal records of batches processed throughout the period and reconciling them to the batch control log. The auditor needs to investigate out-of-balance conditions to determine their cause. For example, assume that the transmittal record for a batch of supplier invoices shows that 100 records with an invoice total of $285,458.86 entered the system. The completed batch log, however, shows that 101 records were processed with a batch total of $288,312.50. What caused this anomaly? Did the system process one record twice due to a programming error? Was an extra record entered into the system during processing? Did the data entry clerk incorrectly calculate the batch control totals? By reviewing and reconciling transaction listings and error logs, the auditor should be able to obtain answers to these questions.