diff --git a/DCC.cpp b/DCC.cpp
index ed2a803..8a6e8e0 100644
--- a/DCC.cpp
+++ b/DCC.cpp
@@ -278,21 +278,39 @@ void DCC::setAccessory(int address, byte port, bool gate, byte onoff /*= 2*/) {
   }
 }
 
-void DCC::setExtendedAccessory(int16_t address, int16_t value, byte repeats) {
+bool DCC::setExtendedAccessory(int16_t address, int16_t value, byte repeats) {
+
+/* From https://www.nmra.org/sites/default/files/s-9.2.1_2012_07.pdf
+
+The Extended Accessory Decoder Control Packet is included for the purpose of transmitting aspect control to signal 
+decoders or data bytes to more complex accessory decoders. Each signal head can display one aspect at a time. 
+{preamble} 0 10AAAAAA 0 0AAA0AA1 0 000XXXXX 0 EEEEEEEE 1
+
+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: 
+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.  
+
+*/
+  if (address != (address & 0x7FF)) return false; // 11 bits
+  if (value != (value & 0x1F)) return false;      // 5 bits 
 
-  // format is 10AAAAAA, 0AAA0AA1, 000XXXXX 
-  if (address != (address & 0x7F)) return;
-  if (value != (value & 0x1F)) return;
     
   byte b[3];
-  b[0]= 0x80 | ((address & 0x7FF)>>5);
-  b[1]= 0x01 | ((address & 0x1c)<<2) | (address & 0x03)<<1;
-  b[2]=value & 0x1F;
+  b[0]= 0x80 | (address>>5);
+  b[1]= 0x01 | (((~address) & 0x1c)<<2) | ((address & 0x03)<<1);
+  b[2]=value;
   DCCWaveform::mainTrack.schedulePacket(b, sizeof(b), repeats);      // Repeat on packet three times
-#if defined(EXRAIL_ACTIVE)
- // TODO RMFT2::activateExtendedEvent(address,value);
-#endif
-}
+  return true;
+  }
 
 //
 // writeCVByteMain: Write a byte with PoM on main. This writes
diff --git a/DCC.h b/DCC.h
index e1aeae6..aa93520 100644
--- a/DCC.h
+++ b/DCC.h
@@ -71,7 +71,7 @@ public:
   static uint32_t getFunctionMap(int cab);
   static void updateGroupflags(byte &flags, int16_t functionNumber);
   static void setAccessory(int address, byte port, bool gate, byte onoff = 2);
-  static void setExtendedAccessory(int16_t address, int16_t value, byte repeats=3);
+  static bool setExtendedAccessory(int16_t address, int16_t value, byte repeats=3);
   static bool writeTextPacket(byte *b, int nBytes);
   
   // ACKable progtrack calls  bitresults callback 0,0 or -1, cv returns value or -1
diff --git a/DCCEXParser.cpp b/DCCEXParser.cpp
index af6c4ee..db78d71 100644
--- a/DCCEXParser.cpp
+++ b/DCCEXParser.cpp
@@ -385,17 +385,12 @@ void DCCEXParser::parseOne(Print *stream, byte *com, RingStream * ringStream)
         }
         return;
     
-    case 'A': // EXTENDED ACCESSORY <A address value>
-        { 
-          // Note: if this happens to match a defined EXRAIL 
-          // DCCX_SIGNAL, then EXRAIL will have intercepted
-          // this command alrerady.   
-          if (params!=2) break; 
-          if (p[0] != (p[0] & 0x7F)) break;
-          if (p[1] != (p[1] & 0x1F)) break; 
-          DCC::setExtendedAccessory(p[0],p[1]);
-        }
-        return;
+    case 'A': // EXTENDED ACCESSORY <A address value> 
+        // Note: if this happens to match a defined EXRAIL 
+        // DCCX_SIGNAL, then EXRAIL will have intercepted
+        // this command alrerady.   
+        if (params==2 && DCC::setExtendedAccessory(p[0],p[1])) return;
+        break;
      
     case 'T': // TURNOUT  <T ...>
         if (parseT(stream, params, p))