This is what the test CSV looks like:

Transaction Date Customer Number Description 1 Payment Method Cheque Number Transaction Type Amount
20160510 3900 Test batch, record 1 CC 5771 CA 100
20160510 1605 Test batch, record 2 Cheque 5780 CA 200
20160510 1694 Test batch, record 3 Debit 5781 CA 300
20160510 1873 Test batch, record 4 Online 5782 CA 400

It will import correctly except that record 1 will have Cheque as the Payment Method, record 2 will have Debit, record 3 will have Online and the record 4 Payment Method will be blank.