be sent. It calls the message controller back, passing an array of data format descriptors that the controller then passes to the transport driver, to see which format it prefers. There will be transport drivers, like the one that uses the Socket library, where any data format will do, so long as the data driver supports the READ_NEXT_BLOCK and WRITE_NEXT_BLOCK calls. Other transport drivers will be more closely coupled with a data driver. For example, the Fax transport driver will require additional inform