This IFM should be used by a ship or base station to send 6-bit ASCII text telegram to other AIS stations. The text telegram can be sent with either binary message 6 or 8. The acknowledge required flag should not be set when using the broadcast message 8.
|Parameter||Number of bits||Description|
|Message ID||6||Identifier for Message 6; always 6|
|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 station|
|Sequence number||2||0-3; see § 5.3.1, Annex 2|
|Destination ID||30||MMSI number of destination station|
|Retransmit flag||1||Retransmit flag should be set upon retransmission: 0 = no retransmission = default; 1 = retransmitted|
|Spare||1||Not used. Should be zero|
|DAC||1||International DAC = 110 = 00000000012|
|FI||0||Function identifier = 010 = 0000002|
|Acknowledge required flag||1||1 = reply is required, optional for addressed binary messages and not used for binary broadcast messages
0 = reply is not required, optional for an addressed binary message and required for binary broadcast messages
|Text sequence number||11||Sequence number to be incremented by the application.
All zeros indicates that sequence numbers are not being used
|Text string||6-906||6-bit ASCII as defined in Table 47, Annex 8. When using this IFM, the number of slots used for transmission should be minimized taking into account Table 29.
For Message 6 the maximum is 906.
|Spare bits||Max 6||Not used for data and should be set to zero. The number of bits should be either 0, 2, 4, or 6 to maintain byte boundaries.
NOTE 1 – When a 6-bit spare is needed to satisfy the 8-bit byte boundary rule, the 6-bit spare will be interpreted as a valid 6‑bit character (all zeros is the “@” character). This is the case when the number of characters is: 1, 5, 9, 13,17, 21, 25, etc.
|Total number of application data bits||112-1 008||For Message 6 the maximum is 920.|
|Maximum number of 6-bit ASCII characters
based upon typical bit stuffing
|Message 25||Message 26|
|NOTE 1 – The 5-slot value accounts for the worst case bit stuffing condition.|