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Appendices
NAK
NAK
NAK
NAK
NAK
ACK
■ Phase 2 with NAK
If the sending station receives a NAK from the receiving station in response to a
transmission block containing text data m, it sends that transmission block again
immediately as shown below.
If the sending station receives an ACK before receiving a NAK 10 times in succes-
sion, it continues the subsequent message transmission.
Sending
station
Receiving
station
Data text m
Data text m
Data text m
Data text m+1
If the sending station receives a NAK 10 times in succession or it fails to send a
same transmission block, it shifts to phase 3 to terminate the message transmis-
sion abnormally. Even if phase 3 terminates normally, the transmission results in
an abnormal end.
Sending
station
Receiving
station
To phase 3.
Occurrence
of an error
Data text m (10)
Data text m (2)
Data text m (1)