diff --git a/src/java/davmail/exchange/ews/ExtendedFieldURI.java b/src/java/davmail/exchange/ews/ExtendedFieldURI.java
index 66690fcb..f3c64b1b 100644
--- a/src/java/davmail/exchange/ews/ExtendedFieldURI.java
+++ b/src/java/davmail/exchange/ews/ExtendedFieldURI.java
@@ -25,10 +25,16 @@ import java.io.Writer;
  * Extended MAPI property.
  */
 public class ExtendedFieldURI implements FieldURI {
-    protected final String propertyTag;
-    protected final String propertyType;
+    protected enum PropertyType {
+        ApplicationTime, ApplicationTimeArray, Binary, BinaryArray, Boolean, CLSID, CLSIDArray, Currency, CurrencyArray,
+        Double, DoubleArray, Error, Float, FloatArray, Integer, IntegerArray, Long, LongArray, Null, Object,
+        ObjectArray, Short, ShortArray, SystemTime, SystemTimeArray, String, StringArray
+    }
 
-    public ExtendedFieldURI(String propertyTag, String propertyType) {
+    protected final String propertyTag;
+    protected final PropertyType propertyType;
+
+    public ExtendedFieldURI(String propertyTag, PropertyType propertyType) {
         this.propertyTag = propertyTag;
         this.propertyType = propertyType;
     }
@@ -37,18 +43,18 @@ public class ExtendedFieldURI implements FieldURI {
         writer.write("<t:ExtendedFieldURI PropertyTag=\"");
         writer.write(propertyTag);
         writer.write("\" PropertyType=\"");
-        writer.write(propertyType);
+        writer.write(propertyType.toString());
         writer.write("\"/>");
     }
 
-    public static final ExtendedFieldURI PR_INSTANCE_KEY = new ExtendedFieldURI("0x0FF6", "Binary");
-    public static final ExtendedFieldURI PR_MESSAGE_SIZE = new ExtendedFieldURI("0x0E08", "Integer");
-    public static final ExtendedFieldURI PR_INTERNET_ARTICLE_NUMBER = new ExtendedFieldURI("0x0E23", "Integer");
-    public static final ExtendedFieldURI JUNK_FLAG = new ExtendedFieldURI("0x1083", "Integer");
-    public static final ExtendedFieldURI PR_FLAG_STATUS = new ExtendedFieldURI("0x1090", "Integer");
-    public static final ExtendedFieldURI PR_MESSAGE_FLAGS = new ExtendedFieldURI("0x0E07", "Integer");
-    public static final ExtendedFieldURI PR_ACTION_FLAG = new ExtendedFieldURI("0x1081", "Integer");
-    public static final ExtendedFieldURI PR_URL_COMP_NAME = new ExtendedFieldURI("0x10F3", "String");
+    public static final ExtendedFieldURI PR_INSTANCE_KEY = new ExtendedFieldURI("0x0FF6", PropertyType.Binary);
+    public static final ExtendedFieldURI PR_MESSAGE_SIZE = new ExtendedFieldURI("0x0E08", PropertyType.Integer);
+    public static final ExtendedFieldURI PR_INTERNET_ARTICLE_NUMBER = new ExtendedFieldURI("0x0E23", PropertyType.Integer);
+    public static final ExtendedFieldURI JUNK_FLAG = new ExtendedFieldURI("0x1083", PropertyType.Integer);
+    public static final ExtendedFieldURI PR_FLAG_STATUS = new ExtendedFieldURI("0x1090", PropertyType.Integer);
+    public static final ExtendedFieldURI PR_MESSAGE_FLAGS = new ExtendedFieldURI("0x0E07", PropertyType.Integer);
+    public static final ExtendedFieldURI PR_ACTION_FLAG = new ExtendedFieldURI("0x1081", PropertyType.Integer);
+    public static final ExtendedFieldURI PR_URL_COMP_NAME = new ExtendedFieldURI("0x10F3", PropertyType.String);
 
 }
 
diff --git a/src/java/davmail/exchange/ews/FolderQueryTraversal.java b/src/java/davmail/exchange/ews/FolderQueryTraversal.java
index 3c2ccda9..65872bdf 100644
--- a/src/java/davmail/exchange/ews/FolderQueryTraversal.java
+++ b/src/java/davmail/exchange/ews/FolderQueryTraversal.java
@@ -24,23 +24,10 @@ import java.io.Writer;
 /**
  * Folder folderQueryTraversalType search mode.
  */
-public final class FolderQueryTraversal {
-    private final String value;
+public final class FolderQueryTraversal extends AttributeOption {
 
     private FolderQueryTraversal(String value) {
-        this.value = value;
-    }
-
-    /**
-     * Write XML content to writer.
-     *
-     * @param writer writer
-     * @throws IOException on error
-     */
-    public void write(Writer writer) throws IOException {
-        writer.write(" Traversal=\"");
-        writer.write(value);
-        writer.write("\"");
+        super("Traversal", value);
     }
 
     /**
diff --git a/src/java/davmail/exchange/ews/MessageDisposition.java b/src/java/davmail/exchange/ews/MessageDisposition.java
index 3bad753f..9c9d0e46 100644
--- a/src/java/davmail/exchange/ews/MessageDisposition.java
+++ b/src/java/davmail/exchange/ews/MessageDisposition.java
@@ -24,23 +24,10 @@ import java.io.Writer;
 /**
  * MessageDisposition flag.
  */
-public class MessageDisposition {
-    private final String value;
+public class MessageDisposition extends AttributeOption {
 
     private MessageDisposition(String value) {
-        this.value = value;
-    }
-
-    /**
-     * Write XML content to writer.
-     *
-     * @param writer writer
-     * @throws java.io.IOException on error
-     */
-    public void write(Writer writer) throws IOException {
-        writer.write(" MessageDisposition=\"");
-        writer.write(value);
-        writer.write("\"");
+        super("MessageDisposition", value);
     }
 
     public static final MessageDisposition SaveOnly = new MessageDisposition("SaveOnly");