In some cases it may be necessary to create the file for an MT101 payment with SWIFT block structure. Then, the header of the file, which contains the SWIFT codes of the sending and receiving institute, is formatted differently.
By default, different logical files, which are called A sequences in MT101, are sent with different orders. If you deactivate the checkbox, these A sequences are concatenated ("chained") and therefore sent together in one order.
Figure: Setting for MT101 payments