More information on MMSIs for the AIVDM document.

1 files changed, 29 insertions, 2 deletions

diff --git a/www/AIVDM.txt b/www/AIVDM.txt
index d5de08db..3f3205e3 100644
--- a/www/AIVDM.txt
+++ b/www/AIVDM.txt
@@ -471,6 +471,27 @@ leading "3", the geography code for North and Centra America and
 Caribbean, emitting 8-digit MMSIs beginning with the U.S. country code
 of 669.
 
+According to <<MMSI>>, different formats of MMSI are used for
+different classes of transmitter. In the format descriptions below, a
+MID is a three-digit decimal literal ranging from 201 to 275 that
+identifies a country or other maritime jurisdiction.  See <<ITU-MID>>
+for a list of MIDs.
+
+.MID formats
+[frame="topbot",options="header"]
+|==============================================================================
+|8MIDXXXXX  | Diver's radio (not used in the U.S. in 2013)
+|MIDXXXXXX  | Ship
+|0MIDXXXXX  | Group of ships; the U.S. Coast Guard, for example, is 03699999
+|00MIDXXXX  | Coastal stations
+|111MIDXXX  | SAR (Search and Rescue) aircraft
+|99MIDXXXX  | Aids to Navigation
+|98MIDXXXX  | Auxilary craft associated with a parent ship
+|970MIDXXX  | AIS SART (Search and Rescue Transmitter)
+|972XXXXXX  | MOB (Man Overboard) device
+|974XXXXXX  | EPIRB (Emergency Position Indicating Radio Beacon) AIS
+|==============================================================================
+
 Detailed descriptions of message types 1-24 follow. Message types 1-22
 are derived from <<IALA>>. Message type 23 was decribed to me by Mike
 Greene based on <<IEC-62287>>.  Message type 24 was described to me by
@@ -4531,8 +4552,11 @@ as the MMSI of the mother ship.  Otherwise the 30 bits describe vessel
 dimensions as in Message Type 5.
 
 According to <<MMSI>>, an MMSI is associated with an auxiliary craft
-when it is of the form 98MIDXXXX where the digits 3, 4 and 5 represent
-the MID and X is any figure from 0 to 9.
+when it is of the form 98XXXYYYY, where (1) the '98' in positions 1
+and 2 is required to designate an auxilary craft, (2) the digits XXX
+in the 3, 4 and 5 positions are the MID (the three-digit country code
+as described in <<ITU-MID>>) and (3) YYYY is any decimal literal from
+0000 to 9999.
 
 === Type 25: Single Slot Binary Message   ===
 
@@ -5253,3 +5277,6 @@ Version 1.42 fixes a typo in the Type 4 message description.
 Version 1.43 describes the ITU-R 1371-4 breakdown of the Type 24
 Vendor ID field and adds information on AIS standards for inland
 waterways. Also Inland AIS standard messages are now covered.
+
+Version 1.44 adds substantial new information on MMSIs and updates
+the <<MMSI link>>, which was stale.