Asynchronous Nack In Dsc (Channel-Attached) Mode - IBM 6400 Programmer's Reference Manual

Figure 37. Asynchronous NACK in DSC (Channel-Attached) Mode. Recommended sequence.
Notes:
1. At the end of this sequence, the printer remains in IPDS mode if no
2. Zero or more WSF with IPDS data sequences may occur before the WSF with
3. If the printer generates an Intervention Required (IR) or Equipment Check
End-of-Chain structured field has been received.
IPDS + ARQ flag is sent. Data is ignored and ATTENTION is repeated on
these transmissions. The Read Modify occurs after the last command.
(EC) NACK, the (CE) (DE) transmission sent after the WSF n+2 command
contains the IR or EC status.
IPDS for Control Units
Appendix B. Summary of IPDS for Control Units
183