Data Link Management - D. This message uses an optional tag that should not be reused. The spare at the end is used to byte align the message.
| Name | NumberOfBits | ArrayLength | Type | Units | Description |
|---|---|---|---|---|---|
| MessageID | 6 | uint | AIS message number. Must be 20 | ||
| RepeatIndicator | 2 | uint | Indicated how many times a message has been repeated 0: default 3: do not repeat any more |
||
| UserID | 30 | uint | Unique ship identification number (MMSI) | ||
| Spare | 2 | uint | Not used. Should be set to zero. | ||
| offset1 | 12 | uint | Reserved offset number | ||
| numslots1 | 4 | uint | Number of reserved consecutive slots | ||
| timeout1 | 3 | uint | min | Time-out value in minutes | |
| increment1 | 11 | uint | Increment to repeast reservation of this block | ||
| offset2 | 12 | uint | Reserved offset number (optional) | ||
| numslots2 | 4 | uint | Number of reserved consecutive slots (optional) | ||
| timeout2 | 3 | uint | min | Time-out value in minutes (optional) | |
| increment2 | 11 | uint | Increment to repeast reservation of this block (optional) | ||
| offset3 | 12 | uint | Reserved offset number (optional) | ||
| numslots3 | 4 | uint | Number of reserved consecutive slots (optional) | ||
| timeout3 | 3 | uint | min | Time-out value in minutes (optional) | |
| increment3 | 11 | uint | Increment to repeast reservation of this block (optional) | ||
| offset4 | 12 | uint | Reserved offset number (optional) | ||
| numslots4 | 4 | uint | Number of reserved consecutive slots (optional) | ||
| timeout4 | 3 | uint | min | Time-out value in minutes (optional) | |
| increment4 | 11 | uint | Increment to repeast reservation of this block (optional) | ||
| variablespare | 6 | uint | This field is a serious pain. This padding makes the message byte aligned |