If the application program is receiving data on a half-duplex conversation when it issues APPCCMD CONTROL=SEND, QUALIFY=ERROR to report a PROGRAM or SERVICE error, return codes of PROGRAM_ERROR_PURGING (X'0034' in RCPRI) or SERVICE_ERROR_PURGING (X'0040' in RCPRI) are reported to the partner. The PURGING return codes are reported to the former sender before any other error data is sent.

Whenever purging is reported, the sending LU should assume that all data sent because the last positive confirmation response has been lost. Receipt of a positive confirmation response indicates that data has been sent by the local transaction program and received by the partner without error.

Application programs also use APPCCMD CONTROL=SEND, QUALIFY=ERROR to respond negatively to a confirmation request on a half-duplex conversation. In such cases, the partner LU receives one of the return codes indicating purging.

When an application program issues APPCCMD CONTROL=SEND, QUALIFY=ERROR on a half-duplex conversation in RECEIVE state, information other than conversation data might be lost. Table 1 shows the return codes VTAM® may fail to report to the application program in this circumstance.

When an allocation error or abnormal deallocation indication is lost, VTAM passes back a return code of DEALLOCATE_NORMAL (X'0080' in RCPRI) on the APPCCMD CONTROL=SEND, QUALIFY=ERROR macroinstruction. When program and service error indications are lost, VTAM passes back a return code of OK (X'0000' in RCPRI). The application program receives no indication that the partner reported an error.

When an application program issues an abnormal termination macroinstruction, either APPCCMD CONTROL=DEALLOC|DEALLOCQ or APPCCMD CONTROL=REJECT, the partner LU receives no indication of whether data has been purged. Because the application program is responding to a rather severe error, however, the LU can assume that purging or truncating has occurred.