This section explains how applications can be written to send data using the HPDT interface. The instructions in this section should be performed by an application after it has determined HPDT support as explained in How support for HPDT is communicated between the application and VTAM and Verifying the session's capabilities. Some of these steps use the IVTCSM macroinstruction. For more information about the IVTCSM macroinstruction, refer to z/OS Communications Server: CSM Guide.