This IFM should be used by a ship or base station to acknowledge a binary message.
This IFM should be returned to the interrogating station only.
Replaced by DAC 1 FI 5 (warning older AIS stations could still use this one)
| Parameter | Number of bits | Description |
|---|---|---|
| IAI/DAC code | 10 | See Annex 2, Table 20 |
| Message sequence number | 11 | Sequence number in the message being acknowledged |
| Spare bits | 3 | Formula for inserting for spare bits |
| Total number of bits | 24 |
Annex 2, Table 20
| DAC | Function identifier | Resulting application identifier (binary) | Resulting application identifier (hex) | Description |
|---|---|---|---|---|
| 1 | 0 | 0000 0000 0100 0000 | 40 | Use of these messages, e.g. for aids-to-navigation, VTS, search and rescue, should be as defined in Annex 5 |
| 1 | 1 | 0000 0000 0100 0001 | 41 | |
| 1 | 2 | 0000 0000 0100 0010 | 42 | |
| 1 | 3 | 0000 0000 0100 0011 | 43 | |
| 1 | … | 0000 0000 01XX XXXX | … | |
| 1 | 63 | 0000 0000 0111 1111 | 007F |