diff --git a/proton-j/src/main/java/org/apache/qpid/proton/codec/messaging/FastPathAcceptedType.java b/proton-j/src/main/java/org/apache/qpid/proton/codec/messaging/FastPathAcceptedType.java
index d9eb991..9e5e96d 100644
--- a/proton-j/src/main/java/org/apache/qpid/proton/codec/messaging/FastPathAcceptedType.java
+++ b/proton-j/src/main/java/org/apache/qpid/proton/codec/messaging/FastPathAcceptedType.java
@@ -22,20 +22,29 @@
 import org.apache.qpid.proton.amqp.UnsignedLong;
 import org.apache.qpid.proton.amqp.messaging.Accepted;
 import org.apache.qpid.proton.codec.AMQPType;
-import org.apache.qpid.proton.codec.FastPathDescribedTypeConstructor;
 import org.apache.qpid.proton.codec.DecodeException;
 import org.apache.qpid.proton.codec.Decoder;
 import org.apache.qpid.proton.codec.DecoderImpl;
 import org.apache.qpid.proton.codec.EncoderImpl;
 import org.apache.qpid.proton.codec.EncodingCodes;
+import org.apache.qpid.proton.codec.FastPathDescribedTypeConstructor;
 import org.apache.qpid.proton.codec.TypeEncoding;
 import org.apache.qpid.proton.codec.WritableBuffer;
 
 public class FastPathAcceptedType implements AMQPType<Accepted>, FastPathDescribedTypeConstructor<Accepted> {
 
+    private static final byte DESCRIPTOR_CODE = 0x24;
+
     private static final Object[] DESCRIPTORS =
     {
-        UnsignedLong.valueOf(0x0000000000000024L), Symbol.valueOf("amqp:accepted:list"),
+        UnsignedLong.valueOf(DESCRIPTOR_CODE), Symbol.valueOf("amqp:accepted:list"),
+    };
+
+    private static final byte[] ACCEPTED_ENCODED_BYTES = new byte[] {
+        EncodingCodes.DESCRIBED_TYPE_INDICATOR,
+        EncodingCodes.SMALLULONG,
+        DESCRIPTOR_CODE,
+        EncodingCodes.LIST0
     };
 
     private final AcceptedType acceptedType;
@@ -108,9 +117,7 @@
     @Override
     public void write(Accepted accepted) {
         WritableBuffer buffer = getEncoder().getBuffer();
-        buffer.put(EncodingCodes.DESCRIBED_TYPE_INDICATOR);
-        getEncoder().writeUnsignedLong(acceptedType.getDescriptor());
-        buffer.put(EncodingCodes.LIST0);
+        buffer.put(ACCEPTED_ENCODED_BYTES, 0, ACCEPTED_ENCODED_BYTES.length);
     }
 
     public static void register(Decoder decoder, EncoderImpl encoder) {
diff --git a/proton-j/src/main/java/org/apache/qpid/proton/codec/messaging/FastPathAmqpSequenceType.java b/proton-j/src/main/java/org/apache/qpid/proton/codec/messaging/FastPathAmqpSequenceType.java
index 611ec10..6a4ebd4 100644
--- a/proton-j/src/main/java/org/apache/qpid/proton/codec/messaging/FastPathAmqpSequenceType.java
+++ b/proton-j/src/main/java/org/apache/qpid/proton/codec/messaging/FastPathAmqpSequenceType.java
@@ -22,19 +22,21 @@
 import org.apache.qpid.proton.amqp.UnsignedLong;
 import org.apache.qpid.proton.amqp.messaging.AmqpSequence;
 import org.apache.qpid.proton.codec.AMQPType;
-import org.apache.qpid.proton.codec.FastPathDescribedTypeConstructor;
 import org.apache.qpid.proton.codec.Decoder;
 import org.apache.qpid.proton.codec.DecoderImpl;
 import org.apache.qpid.proton.codec.EncoderImpl;
 import org.apache.qpid.proton.codec.EncodingCodes;
+import org.apache.qpid.proton.codec.FastPathDescribedTypeConstructor;
 import org.apache.qpid.proton.codec.TypeEncoding;
 import org.apache.qpid.proton.codec.WritableBuffer;
 
 public class FastPathAmqpSequenceType implements AMQPType<AmqpSequence>, FastPathDescribedTypeConstructor<AmqpSequence> {
 
+    private static final byte DESCRIPTOR_CODE = 0x76;
+
     private static final Object[] DESCRIPTORS =
     {
-        UnsignedLong.valueOf(0x0000000000000076L), Symbol.valueOf("amqp:amqp-sequence:list"),
+        UnsignedLong.valueOf(DESCRIPTOR_CODE), Symbol.valueOf("amqp:amqp-sequence:list"),
     };
 
     private final AmqpSequenceType sequenceType;
@@ -90,7 +92,8 @@
     public void write(AmqpSequence sequence) {
         WritableBuffer buffer = getEncoder().getBuffer();
         buffer.put(EncodingCodes.DESCRIBED_TYPE_INDICATOR);
-        getEncoder().writeUnsignedLong(sequenceType.getDescriptor());
+        buffer.put(EncodingCodes.SMALLULONG);
+        buffer.put(DESCRIPTOR_CODE);
         getEncoder().writeObject(sequence.getValue());
     }
 
diff --git a/proton-j/src/main/java/org/apache/qpid/proton/codec/messaging/FastPathAmqpValueType.java b/proton-j/src/main/java/org/apache/qpid/proton/codec/messaging/FastPathAmqpValueType.java
index 7120481..b9d4ee7 100644
--- a/proton-j/src/main/java/org/apache/qpid/proton/codec/messaging/FastPathAmqpValueType.java
+++ b/proton-j/src/main/java/org/apache/qpid/proton/codec/messaging/FastPathAmqpValueType.java
@@ -22,19 +22,21 @@
 import org.apache.qpid.proton.amqp.UnsignedLong;
 import org.apache.qpid.proton.amqp.messaging.AmqpValue;
 import org.apache.qpid.proton.codec.AMQPType;
-import org.apache.qpid.proton.codec.FastPathDescribedTypeConstructor;
 import org.apache.qpid.proton.codec.Decoder;
 import org.apache.qpid.proton.codec.DecoderImpl;
 import org.apache.qpid.proton.codec.EncoderImpl;
 import org.apache.qpid.proton.codec.EncodingCodes;
+import org.apache.qpid.proton.codec.FastPathDescribedTypeConstructor;
 import org.apache.qpid.proton.codec.TypeEncoding;
 import org.apache.qpid.proton.codec.WritableBuffer;
 
 public class FastPathAmqpValueType implements AMQPType<AmqpValue>, FastPathDescribedTypeConstructor<AmqpValue> {
 
+    private static final byte DESCRIPTOR_CODE = 0x77;
+
     private static final Object[] DESCRIPTORS =
     {
-        UnsignedLong.valueOf(0x0000000000000077L), Symbol.valueOf("amqp:amqp-value:*"),
+        UnsignedLong.valueOf(DESCRIPTOR_CODE), Symbol.valueOf("amqp:amqp-value:*"),
     };
 
     private final AmqpValueType valueType;
@@ -90,7 +92,8 @@
     public void write(AmqpValue value) {
         WritableBuffer buffer = getEncoder().getBuffer();
         buffer.put(EncodingCodes.DESCRIBED_TYPE_INDICATOR);
-        getEncoder().writeUnsignedLong(valueType.getDescriptor());
+        buffer.put(EncodingCodes.SMALLULONG);
+        buffer.put(DESCRIPTOR_CODE);
         getEncoder().writeObject(value.getValue());
     }
 
diff --git a/proton-j/src/main/java/org/apache/qpid/proton/codec/messaging/FastPathApplicationPropertiesType.java b/proton-j/src/main/java/org/apache/qpid/proton/codec/messaging/FastPathApplicationPropertiesType.java
index 4eed5e7..08078f3 100644
--- a/proton-j/src/main/java/org/apache/qpid/proton/codec/messaging/FastPathApplicationPropertiesType.java
+++ b/proton-j/src/main/java/org/apache/qpid/proton/codec/messaging/FastPathApplicationPropertiesType.java
@@ -22,20 +22,22 @@
 import org.apache.qpid.proton.amqp.UnsignedLong;
 import org.apache.qpid.proton.amqp.messaging.ApplicationProperties;
 import org.apache.qpid.proton.codec.AMQPType;
-import org.apache.qpid.proton.codec.FastPathDescribedTypeConstructor;
 import org.apache.qpid.proton.codec.Decoder;
 import org.apache.qpid.proton.codec.DecoderImpl;
 import org.apache.qpid.proton.codec.EncoderImpl;
 import org.apache.qpid.proton.codec.EncodingCodes;
+import org.apache.qpid.proton.codec.FastPathDescribedTypeConstructor;
 import org.apache.qpid.proton.codec.MapType;
 import org.apache.qpid.proton.codec.TypeEncoding;
 import org.apache.qpid.proton.codec.WritableBuffer;
 
 public class FastPathApplicationPropertiesType implements AMQPType<ApplicationProperties>, FastPathDescribedTypeConstructor<ApplicationProperties> {
 
+    private static final byte DESCRIPTOR_CODE = 0x74;
+
     private static final Object[] DESCRIPTORS =
     {
-        UnsignedLong.valueOf(0x0000000000000074L), Symbol.valueOf("amqp:application-properties:map"),
+        UnsignedLong.valueOf(DESCRIPTOR_CODE), Symbol.valueOf("amqp:application-properties:map"),
     };
 
     private final ApplicationPropertiesType propertiesType;
@@ -92,7 +94,8 @@
         WritableBuffer buffer = getEncoder().getBuffer();
 
         buffer.put(EncodingCodes.DESCRIBED_TYPE_INDICATOR);
-        getEncoder().writeUnsignedLong(propertiesType.getDescriptor());
+        buffer.put(EncodingCodes.SMALLULONG);
+        buffer.put(DESCRIPTOR_CODE);
 
         MapType mapType = (MapType) getEncoder().getType(val.getValue());
 
diff --git a/proton-j/src/main/java/org/apache/qpid/proton/codec/messaging/FastPathDataType.java b/proton-j/src/main/java/org/apache/qpid/proton/codec/messaging/FastPathDataType.java
index 75a7543..a3cfb2a 100644
--- a/proton-j/src/main/java/org/apache/qpid/proton/codec/messaging/FastPathDataType.java
+++ b/proton-j/src/main/java/org/apache/qpid/proton/codec/messaging/FastPathDataType.java
@@ -22,19 +22,21 @@
 import org.apache.qpid.proton.amqp.UnsignedLong;
 import org.apache.qpid.proton.amqp.messaging.Data;
 import org.apache.qpid.proton.codec.AMQPType;
-import org.apache.qpid.proton.codec.FastPathDescribedTypeConstructor;
 import org.apache.qpid.proton.codec.Decoder;
 import org.apache.qpid.proton.codec.DecoderImpl;
 import org.apache.qpid.proton.codec.EncoderImpl;
 import org.apache.qpid.proton.codec.EncodingCodes;
+import org.apache.qpid.proton.codec.FastPathDescribedTypeConstructor;
 import org.apache.qpid.proton.codec.TypeEncoding;
 import org.apache.qpid.proton.codec.WritableBuffer;
 
 public class FastPathDataType implements AMQPType<Data>, FastPathDescribedTypeConstructor<Data> {
 
+    private static final byte DESCRIPTOR_CODE = 0x75;
+
     private static final Object[] DESCRIPTORS =
     {
-        UnsignedLong.valueOf(0x0000000000000075L), Symbol.valueOf("amqp:data:binary"),
+        UnsignedLong.valueOf(DESCRIPTOR_CODE), Symbol.valueOf("amqp:data:binary"),
     };
 
     private final DataType dataType;
@@ -90,7 +92,8 @@
     public void write(Data data) {
         WritableBuffer buffer = getEncoder().getBuffer();
         buffer.put(EncodingCodes.DESCRIBED_TYPE_INDICATOR);
-        getEncoder().writeUnsignedLong(dataType.getDescriptor());
+        buffer.put(EncodingCodes.SMALLULONG);
+        buffer.put(DESCRIPTOR_CODE);
         getEncoder().writeBinary(data.getValue());
     }
 
diff --git a/proton-j/src/main/java/org/apache/qpid/proton/codec/messaging/FastPathDeliveryAnnotationsType.java b/proton-j/src/main/java/org/apache/qpid/proton/codec/messaging/FastPathDeliveryAnnotationsType.java
index 4252393..acf91dc 100644
--- a/proton-j/src/main/java/org/apache/qpid/proton/codec/messaging/FastPathDeliveryAnnotationsType.java
+++ b/proton-j/src/main/java/org/apache/qpid/proton/codec/messaging/FastPathDeliveryAnnotationsType.java
@@ -33,9 +33,11 @@
 
 public class FastPathDeliveryAnnotationsType implements AMQPType<DeliveryAnnotations>, FastPathDescribedTypeConstructor<DeliveryAnnotations> {
 
+    private static final byte DESCRIPTOR_CODE = 0x71;
+
     private static final Object[] DESCRIPTORS =
     {
-        UnsignedLong.valueOf(0x0000000000000071L), Symbol.valueOf("amqp:delivery-annotations:map"),
+        UnsignedLong.valueOf(DESCRIPTOR_CODE), Symbol.valueOf("amqp:delivery-annotations:map"),
     };
 
     private final DeliveryAnnotationsType annotationsType;
@@ -93,7 +95,8 @@
         WritableBuffer buffer = getEncoder().getBuffer();
 
         buffer.put(EncodingCodes.DESCRIBED_TYPE_INDICATOR);
-        getEncoder().writeUnsignedLong(annotationsType.getDescriptor());
+        buffer.put(EncodingCodes.SMALLULONG);
+        buffer.put(DESCRIPTOR_CODE);
 
         MapType mapType = (MapType) getEncoder().getType(val.getValue());
 
diff --git a/proton-j/src/main/java/org/apache/qpid/proton/codec/messaging/FastPathFooterType.java b/proton-j/src/main/java/org/apache/qpid/proton/codec/messaging/FastPathFooterType.java
index d1b0d40..88f690f 100644
--- a/proton-j/src/main/java/org/apache/qpid/proton/codec/messaging/FastPathFooterType.java
+++ b/proton-j/src/main/java/org/apache/qpid/proton/codec/messaging/FastPathFooterType.java
@@ -33,9 +33,11 @@
 
 public class FastPathFooterType implements AMQPType<Footer>, FastPathDescribedTypeConstructor<Footer> {
 
+    private static final byte DESCRIPTOR_CODE = 0x78;
+
     private static final Object[] DESCRIPTORS =
     {
-        UnsignedLong.valueOf(0x0000000000000078L), Symbol.valueOf("amqp:footer:map"),
+        UnsignedLong.valueOf(DESCRIPTOR_CODE), Symbol.valueOf("amqp:footer:map"),
     };
 
     private final FooterType footerType;
@@ -92,7 +94,8 @@
         WritableBuffer buffer = getEncoder().getBuffer();
 
         buffer.put(EncodingCodes.DESCRIBED_TYPE_INDICATOR);
-        getEncoder().writeUnsignedLong(footerType.getDescriptor());
+        buffer.put(EncodingCodes.SMALLULONG);
+        buffer.put(DESCRIPTOR_CODE);
 
         MapType mapType = (MapType) getEncoder().getType(val.getValue());
 
diff --git a/proton-j/src/main/java/org/apache/qpid/proton/codec/messaging/FastPathHeaderType.java b/proton-j/src/main/java/org/apache/qpid/proton/codec/messaging/FastPathHeaderType.java
index 06d8026..2562e57 100644
--- a/proton-j/src/main/java/org/apache/qpid/proton/codec/messaging/FastPathHeaderType.java
+++ b/proton-j/src/main/java/org/apache/qpid/proton/codec/messaging/FastPathHeaderType.java
@@ -22,20 +22,22 @@
 import org.apache.qpid.proton.amqp.UnsignedLong;
 import org.apache.qpid.proton.amqp.messaging.Header;
 import org.apache.qpid.proton.codec.AMQPType;
-import org.apache.qpid.proton.codec.FastPathDescribedTypeConstructor;
 import org.apache.qpid.proton.codec.DecodeException;
 import org.apache.qpid.proton.codec.Decoder;
 import org.apache.qpid.proton.codec.DecoderImpl;
 import org.apache.qpid.proton.codec.EncoderImpl;
 import org.apache.qpid.proton.codec.EncodingCodes;
+import org.apache.qpid.proton.codec.FastPathDescribedTypeConstructor;
 import org.apache.qpid.proton.codec.TypeEncoding;
 import org.apache.qpid.proton.codec.WritableBuffer;
 
 public class FastPathHeaderType implements AMQPType<Header>, FastPathDescribedTypeConstructor<Header> {
 
+    private static final byte DESCRIPTOR_CODE = 0x70;
+
     private static final Object[] DESCRIPTORS =
     {
-        UnsignedLong.valueOf(0x0000000000000070L), Symbol.valueOf("amqp:header:list"),
+        UnsignedLong.valueOf(DESCRIPTOR_CODE), Symbol.valueOf("amqp:header:list"),
     };
 
     private final HeaderType headerType;
@@ -140,11 +142,12 @@
         byte encodingCode = deduceEncodingCode(value, count);
 
         buffer.put(EncodingCodes.DESCRIBED_TYPE_INDICATOR);
-        getEncoder().writeUnsignedLong(headerType.getDescriptor());
+        buffer.put(EncodingCodes.SMALLULONG);
+        buffer.put(DESCRIPTOR_CODE);
+        buffer.put(encodingCode);
 
         // Optimized step, no other data to be written.
-        if (count == 0 || encodingCode == EncodingCodes.LIST0) {
-            buffer.put(EncodingCodes.LIST0);
+        if (encodingCode == EncodingCodes.LIST0) {
             return;
         }
 
@@ -152,10 +155,8 @@
 
         if (encodingCode == EncodingCodes.LIST8) {
             fieldWidth = 1;
-            buffer.put(EncodingCodes.LIST8);
         } else {
             fieldWidth = 4;
-            buffer.put(EncodingCodes.LIST32);
         }
 
         int startIndex = buffer.position();
diff --git a/proton-j/src/main/java/org/apache/qpid/proton/codec/messaging/FastPathMessageAnnotationsType.java b/proton-j/src/main/java/org/apache/qpid/proton/codec/messaging/FastPathMessageAnnotationsType.java
index 6d32004..195e4b5 100644
--- a/proton-j/src/main/java/org/apache/qpid/proton/codec/messaging/FastPathMessageAnnotationsType.java
+++ b/proton-j/src/main/java/org/apache/qpid/proton/codec/messaging/FastPathMessageAnnotationsType.java
@@ -22,20 +22,22 @@
 import org.apache.qpid.proton.amqp.UnsignedLong;
 import org.apache.qpid.proton.amqp.messaging.MessageAnnotations;
 import org.apache.qpid.proton.codec.AMQPType;
-import org.apache.qpid.proton.codec.FastPathDescribedTypeConstructor;
 import org.apache.qpid.proton.codec.Decoder;
 import org.apache.qpid.proton.codec.DecoderImpl;
 import org.apache.qpid.proton.codec.EncoderImpl;
 import org.apache.qpid.proton.codec.EncodingCodes;
+import org.apache.qpid.proton.codec.FastPathDescribedTypeConstructor;
 import org.apache.qpid.proton.codec.MapType;
 import org.apache.qpid.proton.codec.TypeEncoding;
 import org.apache.qpid.proton.codec.WritableBuffer;
 
 public class FastPathMessageAnnotationsType implements AMQPType<MessageAnnotations>, FastPathDescribedTypeConstructor<MessageAnnotations> {
 
+    private static final byte DESCRIPTOR_CODE = 0x72;
+
     private static final Object[] DESCRIPTORS =
     {
-        UnsignedLong.valueOf(0x0000000000000072L), Symbol.valueOf("amqp:message-annotations:map"),
+        UnsignedLong.valueOf(DESCRIPTOR_CODE), Symbol.valueOf("amqp:message-annotations:map"),
     };
 
     private final MessageAnnotationsType annotationsType;
@@ -93,7 +95,8 @@
         WritableBuffer buffer = getEncoder().getBuffer();
 
         buffer.put(EncodingCodes.DESCRIBED_TYPE_INDICATOR);
-        getEncoder().writeUnsignedLong(annotationsType.getDescriptor());
+        buffer.put(EncodingCodes.SMALLULONG);
+        buffer.put(DESCRIPTOR_CODE);
 
         MapType mapType = (MapType) getEncoder().getType(val.getValue());
 
diff --git a/proton-j/src/main/java/org/apache/qpid/proton/codec/messaging/FastPathPropertiesType.java b/proton-j/src/main/java/org/apache/qpid/proton/codec/messaging/FastPathPropertiesType.java
index e071ea9..3d5c7c4 100644
--- a/proton-j/src/main/java/org/apache/qpid/proton/codec/messaging/FastPathPropertiesType.java
+++ b/proton-j/src/main/java/org/apache/qpid/proton/codec/messaging/FastPathPropertiesType.java
@@ -22,20 +22,22 @@
 import org.apache.qpid.proton.amqp.UnsignedLong;
 import org.apache.qpid.proton.amqp.messaging.Properties;
 import org.apache.qpid.proton.codec.AMQPType;
-import org.apache.qpid.proton.codec.FastPathDescribedTypeConstructor;
 import org.apache.qpid.proton.codec.DecodeException;
 import org.apache.qpid.proton.codec.Decoder;
 import org.apache.qpid.proton.codec.DecoderImpl;
 import org.apache.qpid.proton.codec.EncoderImpl;
 import org.apache.qpid.proton.codec.EncodingCodes;
+import org.apache.qpid.proton.codec.FastPathDescribedTypeConstructor;
 import org.apache.qpid.proton.codec.TypeEncoding;
 import org.apache.qpid.proton.codec.WritableBuffer;
 
 public class FastPathPropertiesType implements AMQPType<Properties>, FastPathDescribedTypeConstructor<Properties> {
 
+    private static final byte DESCRIPTOR_CODE = 0x73;
+
     private static final Object[] DESCRIPTORS =
     {
-        UnsignedLong.valueOf(0x0000000000000073L), Symbol.valueOf("amqp:properties:list"),
+        UnsignedLong.valueOf(DESCRIPTOR_CODE), Symbol.valueOf("amqp:properties:list"),
     };
 
     private final PropertiesType propertiesType;
@@ -164,11 +166,12 @@
         byte encodingCode = deduceEncodingCode(value, count);
 
         buffer.put(EncodingCodes.DESCRIBED_TYPE_INDICATOR);
-        getEncoder().writeUnsignedLong(propertiesType.getDescriptor());
+        buffer.put(EncodingCodes.SMALLULONG);
+        buffer.put(DESCRIPTOR_CODE);
+        buffer.put(encodingCode);
 
         // Optimized step, no other data to be written.
-        if (count == 0 || encodingCode == EncodingCodes.LIST0) {
-            buffer.put(EncodingCodes.LIST0);
+        if (encodingCode == EncodingCodes.LIST0) {
             return;
         }
 
@@ -176,10 +179,8 @@
 
         if (encodingCode == EncodingCodes.LIST8) {
             fieldWidth = 1;
-            buffer.put(EncodingCodes.LIST8);
         } else {
             fieldWidth = 4;
-            buffer.put(EncodingCodes.LIST32);
         }
 
         int startIndex = buffer.position();
diff --git a/proton-j/src/main/java/org/apache/qpid/proton/codec/transport/FastPathDispositionType.java b/proton-j/src/main/java/org/apache/qpid/proton/codec/transport/FastPathDispositionType.java
index c329aa7..4424cfa 100644
--- a/proton-j/src/main/java/org/apache/qpid/proton/codec/transport/FastPathDispositionType.java
+++ b/proton-j/src/main/java/org/apache/qpid/proton/codec/transport/FastPathDispositionType.java
@@ -26,20 +26,30 @@
 import org.apache.qpid.proton.amqp.transport.Disposition;
 import org.apache.qpid.proton.amqp.transport.Role;
 import org.apache.qpid.proton.codec.AMQPType;
-import org.apache.qpid.proton.codec.FastPathDescribedTypeConstructor;
 import org.apache.qpid.proton.codec.DecodeException;
 import org.apache.qpid.proton.codec.Decoder;
 import org.apache.qpid.proton.codec.DecoderImpl;
 import org.apache.qpid.proton.codec.EncoderImpl;
 import org.apache.qpid.proton.codec.EncodingCodes;
+import org.apache.qpid.proton.codec.FastPathDescribedTypeConstructor;
 import org.apache.qpid.proton.codec.TypeEncoding;
 import org.apache.qpid.proton.codec.WritableBuffer;
 
 public class FastPathDispositionType implements AMQPType<Disposition>, FastPathDescribedTypeConstructor<Disposition> {
 
+    private static final byte DESCRIPTOR_CODE = 0x15;
+    private static final byte ACCEPTED_DESCRIPTOR_CODE = 0x24;
+
     private static final Object[] DESCRIPTORS =
     {
-        UnsignedLong.valueOf(0x0000000000000015L), Symbol.valueOf("amqp:disposition:list"),
+        UnsignedLong.valueOf(DESCRIPTOR_CODE), Symbol.valueOf("amqp:disposition:list"),
+    };
+
+    private static final byte[] ACCEPTED_ENCODED_BYTES = new byte[] {
+        EncodingCodes.DESCRIBED_TYPE_INDICATOR,
+        EncodingCodes.SMALLULONG,
+        ACCEPTED_DESCRIPTOR_CODE,
+        EncodingCodes.LIST0
     };
 
     private final DispositionType dispositionType;
@@ -148,16 +158,16 @@
         byte encodingCode = deduceEncodingCode(disposition, count);
 
         buffer.put(EncodingCodes.DESCRIBED_TYPE_INDICATOR);
-        getEncoder().writeUnsignedLong(dispositionType.getDescriptor());
+        buffer.put(EncodingCodes.SMALLULONG);
+        buffer.put(DESCRIPTOR_CODE);
+        buffer.put(encodingCode);
 
         final int fieldWidth;
 
         if (encodingCode == EncodingCodes.LIST8) {
             fieldWidth = 1;
-            buffer.put(EncodingCodes.LIST8);
         } else {
             fieldWidth = 4;
-            buffer.put(EncodingCodes.LIST32);
         }
 
         int startIndex = buffer.position();
@@ -204,7 +214,11 @@
                 getEncoder().writeBoolean(disposition.getSettled());
                 break;
             case 4:
-                getEncoder().writeObject(disposition.getState());
+                if (Accepted.getInstance().equals(disposition.getState())) {
+                    getEncoder().getBuffer().put(ACCEPTED_ENCODED_BYTES, 0, ACCEPTED_ENCODED_BYTES.length);
+                } else {
+                    getEncoder().writeObject(disposition.getState());
+                }
                 break;
             case 5:
                 getEncoder().writeBoolean(disposition.getBatchable());
diff --git a/proton-j/src/main/java/org/apache/qpid/proton/codec/transport/FastPathFlowType.java b/proton-j/src/main/java/org/apache/qpid/proton/codec/transport/FastPathFlowType.java
index 6f500be..7ed89e4 100644
--- a/proton-j/src/main/java/org/apache/qpid/proton/codec/transport/FastPathFlowType.java
+++ b/proton-j/src/main/java/org/apache/qpid/proton/codec/transport/FastPathFlowType.java
@@ -22,20 +22,22 @@
 import org.apache.qpid.proton.amqp.UnsignedLong;
 import org.apache.qpid.proton.amqp.transport.Flow;
 import org.apache.qpid.proton.codec.AMQPType;
-import org.apache.qpid.proton.codec.FastPathDescribedTypeConstructor;
 import org.apache.qpid.proton.codec.DecodeException;
 import org.apache.qpid.proton.codec.Decoder;
 import org.apache.qpid.proton.codec.DecoderImpl;
 import org.apache.qpid.proton.codec.EncoderImpl;
 import org.apache.qpid.proton.codec.EncodingCodes;
+import org.apache.qpid.proton.codec.FastPathDescribedTypeConstructor;
 import org.apache.qpid.proton.codec.TypeEncoding;
 import org.apache.qpid.proton.codec.WritableBuffer;
 
 public class FastPathFlowType implements AMQPType<Flow>, FastPathDescribedTypeConstructor<Flow> {
 
+    private static final byte DESCRIPTOR_CODE = 0x13;
+
     private static final Object[] DESCRIPTORS =
     {
-        UnsignedLong.valueOf(0x0000000000000013L), Symbol.valueOf("amqp:flow:list"),
+        UnsignedLong.valueOf(DESCRIPTOR_CODE), Symbol.valueOf("amqp:flow:list"),
     };
 
     private final FlowType flowType;
@@ -159,16 +161,16 @@
         byte encodingCode = deduceEncodingCode(flow, count);
 
         buffer.put(EncodingCodes.DESCRIBED_TYPE_INDICATOR);
-        getEncoder().writeUnsignedLong(flowType.getDescriptor());
+        buffer.put(EncodingCodes.SMALLULONG);
+        buffer.put(DESCRIPTOR_CODE);
+        buffer.put(encodingCode);
 
         final int fieldWidth;
 
         if (encodingCode == EncodingCodes.LIST8) {
             fieldWidth = 1;
-            buffer.put(EncodingCodes.LIST8);
         } else {
             fieldWidth = 4;
-            buffer.put(EncodingCodes.LIST32);
         }
 
         int startIndex = buffer.position();
diff --git a/proton-j/src/main/java/org/apache/qpid/proton/codec/transport/FastPathTransferType.java b/proton-j/src/main/java/org/apache/qpid/proton/codec/transport/FastPathTransferType.java
index 79842db..d27e59c 100644
--- a/proton-j/src/main/java/org/apache/qpid/proton/codec/transport/FastPathTransferType.java
+++ b/proton-j/src/main/java/org/apache/qpid/proton/codec/transport/FastPathTransferType.java
@@ -25,12 +25,12 @@
 import org.apache.qpid.proton.amqp.transport.ReceiverSettleMode;
 import org.apache.qpid.proton.amqp.transport.Transfer;
 import org.apache.qpid.proton.codec.AMQPType;
-import org.apache.qpid.proton.codec.FastPathDescribedTypeConstructor;
 import org.apache.qpid.proton.codec.DecodeException;
 import org.apache.qpid.proton.codec.Decoder;
 import org.apache.qpid.proton.codec.DecoderImpl;
 import org.apache.qpid.proton.codec.EncoderImpl;
 import org.apache.qpid.proton.codec.EncodingCodes;
+import org.apache.qpid.proton.codec.FastPathDescribedTypeConstructor;
 import org.apache.qpid.proton.codec.TypeEncoding;
 import org.apache.qpid.proton.codec.WritableBuffer;
 
@@ -39,9 +39,11 @@
  */
 public class FastPathTransferType implements AMQPType<Transfer>, FastPathDescribedTypeConstructor<Transfer> {
 
+    private static final byte DESCRIPTOR_CODE = 0x14;
+
     private static final Object[] DESCRIPTORS =
     {
-        UnsignedLong.valueOf(0x0000000000000014L), Symbol.valueOf("amqp:transfer:list"),
+        UnsignedLong.valueOf(DESCRIPTOR_CODE), Symbol.valueOf("amqp:transfer:list"),
     };
 
     private final TransferType transferType;
@@ -166,16 +168,16 @@
         byte encodingCode = deduceEncodingCode(value, count);
 
         buffer.put(EncodingCodes.DESCRIBED_TYPE_INDICATOR);
-        getEncoder().writeUnsignedLong(transferType.getDescriptor());
+        buffer.put(EncodingCodes.SMALLULONG);
+        buffer.put(DESCRIPTOR_CODE);
+        buffer.put(encodingCode);
 
         final int fieldWidth;
 
         if (encodingCode == EncodingCodes.LIST8) {
             fieldWidth = 1;
-            buffer.put(EncodingCodes.LIST8);
         } else {
             fieldWidth = 4;
-            buffer.put(EncodingCodes.LIST32);
         }
 
         int startIndex = buffer.position();