Format Flag (Bit 25)

The beacon message format is identified at bit 25 for all message formats. For this implementation of this protocol, this bit is set to the value indicated in the graphic you just clicked on (0 for short message formats, 1 for long message formats).

Protocol Flag (Bit 26)

The protocol type is identified at bit 26 for all message formats. For this implementation of this protocol, this bit is set to the value indicated in the graphic you just clicked on (0 for a Standard Location Protocol or National Location Protocol, 1 for a User Protocol or User Location Protocol).

Fixed Bits

For the implementation of this protocol, these bits are set to the values indicated in the graphic you just clicked on.

Non-Protected Data Field (Bits 107 – 112 of short format messages)

The non-protected data field refers to bits 107 – 112 of short format messages. The term “non-protected” derives from the fact that these bits are not protected by the beacons error correcting code.

The content of these bits are defined by the specific protocol used in the beacon.

Specific Beacon Number

These bits are used to identify the specific beacon in cases where there may be several beacons on the same vessel. The first or the only float free beacon shall be coded with a modified-Baudot zero (001101); additional beacons shall be numbered consecutively using modified-Baudot characters 1 to 9 and A to Z.