/// <summary>
        /// Reads an *implementation specific* bundled .NET object, including (as options) type-metadata, identity/re-use, etc.
        /// </summary>
        public static object ReadNetObject(object value, ProtoReader source, int key, Type type, NetObjectOptions options)
        {
            SubItemToken token = ProtoReader.StartSubItem(source);
            int          fieldNumber;
            int          newObjectKey = -1, newTypeKey = -1, tmp;

            while ((fieldNumber = source.ReadFieldHeader()) > 0)
            {
                switch (fieldNumber)
                {
                case FieldExistingObjectKey:
                    tmp   = source.ReadInt32();
                    value = source.NetCache.GetKeyedObject(tmp);
                    break;

                case FieldNewObjectKey:
                    newObjectKey = source.ReadInt32();
                    break;

                case FieldExistingTypeKey:
                    tmp  = source.ReadInt32();
                    type = (Type)source.NetCache.GetKeyedObject(tmp);
                    key  = source.GetTypeKey(ref type);
                    break;

                case FieldNewTypeKey:
                    newTypeKey = source.ReadInt32();
                    break;

                case FieldTypeName:
                    string typeName = source.ReadString();
                    type = source.DeserializeType(typeName);
                    if (type == null)
                    {
                        throw new ProtoException("Unable to resolve type: " + typeName + " (you can use the TypeModel.DynamicTypeFormatting event to provide a custom mapping)");
                    }
                    if (type == typeof(string))
                    {
                        key = -1;
                    }
                    else
                    {
                        key = source.GetTypeKey(ref type);
                        if (key < 0)
                        {
                            throw new InvalidOperationException("Dynamic type is not a contract-type: " + type.Name);
                        }
                    }
                    break;

                case FieldObject:
                    bool isString = type == typeof(string);
                    bool wasNull  = value == null;
                    bool lateSet  = wasNull && (isString || ((options & NetObjectOptions.LateSet) != 0));

                    if (newObjectKey >= 0 && !lateSet)
                    {
                        if (value == null)
                        {
                            source.TrapNextObject(newObjectKey);
                        }
                        else
                        {
                            source.NetCache.SetKeyedObject(newObjectKey, value);
                        }
                        if (newTypeKey >= 0)
                        {
                            source.NetCache.SetKeyedObject(newTypeKey, type);
                        }
                    }
                    object oldValue = value;
                    if (isString)
                    {
                        value = source.ReadString();
                    }
                    else
                    {
                        value = ProtoReader.ReadTypedObject(oldValue, key, source, type);
                    }

                    if (newObjectKey >= 0)
                    {
                        if (wasNull && !lateSet)
                        {     // this both ensures (via exception) that it *was* set, and makes sure we don't shout
                            // about changed references
                            oldValue = source.NetCache.GetKeyedObject(newObjectKey);
                        }
                        if (lateSet)
                        {
                            source.NetCache.SetKeyedObject(newObjectKey, value);
                            if (newTypeKey >= 0)
                            {
                                source.NetCache.SetKeyedObject(newTypeKey, type);
                            }
                        }
                    }
                    if (newObjectKey >= 0 && !lateSet && !ReferenceEquals(oldValue, value))
                    {
                        throw new ProtoException("A reference-tracked object changed reference during deserialization");
                    }
                    if (newObjectKey < 0 && newTypeKey >= 0)
                    {      // have a new type, but not a new object
                        source.NetCache.SetKeyedObject(newTypeKey, type);
                    }
                    break;

                default:
                    source.SkipField();
                    break;
                }
            }
            if (newObjectKey >= 0 && (options & NetObjectOptions.AsReference) == 0)
            {
                throw new ProtoException("Object key in input stream, but reference-tracking was not expected");
            }
            ProtoReader.EndSubItem(token, source);

            return(value);
        }