diff --git a/DCC.cpp b/DCC.cpp
index 8a6e8e0..a435eeb 100644
--- a/DCC.cpp
+++ b/DCC.cpp
@@ -289,28 +289,45 @@ decoders or data bytes to more complex accessory decoders. Each signal head can
 XXXXX is for a single head. A value of 00000 for XXXXX indicates the absolute stop aspect. All other aspects 
 represented by the values for XXXXX are determined by the signaling system used and the prototype being 
 modeled.
-*/
-/* CAH Notes: 
+
+From https://normen.railcommunity.de/RCN-213.pdf:
+
+More information is in RCN-213 about how the address bits are organized.
+preamble -0- 1 0 A7 A6 A5 A4 A3 A2 -0- 0 ^A10 ^A9 ^A8 0 A1 A0 1 -0- ....
+
 Thus in byte packet form the format is 10AAAAAA, 0AAA0AA1, 000XXXXX
 
-Note that the Basic accessory format mentions 
-"By convention these bits (bits 4-6 of the second data byte) are in ones complement"
-but this note is absent from the advanced packet description.
-The (~address) construct below applies this because this appears to be 
-required.  
+Die Adresse für den ersten erweiterten Zubehördecoder ist wie bei den einfachen
+Zubehördecodern die Adresse 4 = 1000-0001 0111-0001 . Diese Adresse wird in
+Anwenderdialogen als Adresse 1 dargestellt.
 
+This means that the first address shown to the user as "1" is mapped
+to internal address 4.
+
+Note that the Basic accessory format mentions "By convention these
+bits (bits 4-6 of the second data byte) are in ones complement" but
+this note is absent from the advanced packet description. The
+english translation does not mention that the address format for
+the advanced packet follows the one for the basic packet but
+according to the RCN-213 this is the case.
+
+We allow for addresses from -3 to 2047-3 as that allows to address the
+whole range of the 11 bits sent to track.
 */
-  if (address != (address & 0x7FF)) return false; // 11 bits
-  if (value != (value & 0x1F)) return false;      // 5 bits 
+  if ((address > 2044) || (address < -3)) return false; // 2047-3, 11 bits but offset 3
+  if (value != (value & 0x1F)) return false;            // 5 bits
 
-    
+  address+=3;                        // +3 offset according to RCN-213
   byte b[3];
-  b[0]= 0x80 | (address>>5);
-  b[1]= 0x01 | (((~address) & 0x1c)<<2) | ((address & 0x03)<<1);
+  b[0]= 0x80                         // bits always on
+    | ((address>>2) & 0x3F);         // shift out 2, mask out used bits
+  b[1]= 0x01                         // bits always on
+    | (((~(address>>8)) & 0x07)<<4)  // shift out 8, invert, mask 3 bits, shift up 4
+    | ((address & 0x03)<<1);         // mask 2 bits, shift up 1
   b[2]=value;
-  DCCWaveform::mainTrack.schedulePacket(b, sizeof(b), repeats);      // Repeat on packet three times
+  DCCWaveform::mainTrack.schedulePacket(b, sizeof(b), repeats);
   return true;
-  }
+}
 
 //
 // writeCVByteMain: Write a byte with PoM on main. This writes