Binary acknowledge

msg_ID: 
7
Description: 
Acknowledgement of received addressed binary data
Priority: 
1
Access scheme: 
RATDMA
ITDMA
FATDMA
Communication state: 
N/A
Transmitted by: 
Mobile station
Base station

Message 7 should be used as an acknowledgement of up to four Message 6 messages received (see § 5.3.1, Annex 2) and should be transmitted on the channel, where the addressed message to be acknowledged was received.
These acknowledgements should be applicable only to the VHF data link (see § 5.3.1, Annex 2). Other means must be employed for acknowledging applications.

TABLE 56
Parameter Number of bits Description
Message ID 6 Identifier for Messages 7 or 13
7 = binary acknowledge
13 = safety related acknowledge
Repeat indicator 2 Used by the repeater to indicate how many times a message has been repeated. See § 4.6.1, Annex 2; 0-3; 0 = default; 3 = do not repeat any more
Source ID 30 MMSI number of source of this acknowledge (ACK)
Spare 2 Not used. Should be set to zero. Reserved for future use
Destination ID1 30 MMSI number of first destination of this ACK
Sequence number for ID1 2 Sequence number of message to be acknowledged; 0-3
Destination ID2 30 MMSI number of second destination of this ACK; should be omitted if no destination ID2
Sequence number for ID2 2 Sequence number of message to be acknowledged; 0-3; should be omitted if no destination ID2
Destination ID3 30 MMSI number of third destination of this ACK; should be omitted if no destination ID3
Sequence number for ID3 2 Sequence number of message to be acknowledged; 0-3; should be omitted if no destination ID3
Destination ID4 30 MMSI number of fourth destination of this ACK; should be omitted if no destination ID4
Sequence number for ID4 2 Sequence number of message to be acknowledged; 0-3. Should be omitted if there is no destination ID4
Number of bits 72-168