diff --git a/src/main/java/ar/com/fernandospr/wns/client/WnsResourceBuilder.java b/src/main/java/ar/com/fernandospr/wns/client/WnsResourceBuilder.java
index 098688d..2295abe 100644
--- a/src/main/java/ar/com/fernandospr/wns/client/WnsResourceBuilder.java
+++ b/src/main/java/ar/com/fernandospr/wns/client/WnsResourceBuilder.java
@@ -6,7 +6,9 @@
 
 import ar.com.fernandospr.wns.model.WnsAbstractNotification;
 import ar.com.fernandospr.wns.model.WnsNotificationRequestOptional;
+import ar.com.fernandospr.wns.model.types.WnsCachePolicyTypeEnum;
 import ar.com.fernandospr.wns.model.types.WnsNotificationType;
+import ar.com.fernandospr.wns.model.types.WnsRequestForStatusTypeEnum;
 
 
 public abstract class WnsResourceBuilder {
@@ -24,10 +26,10 @@ public Invocation.Builder build(WebTarget target, WnsAbstractNotification notifi
 	
 	protected void addOptionalHeaders(Invocation.Builder webResourceBuilder, WnsNotificationRequestOptional optional) {
 		if (optional != null) {
-			if (!emptyString(optional.cachePolicy)) {
+			if (optional.cachePolicy != WnsCachePolicyTypeEnum.DEFAULT) {
 				webResourceBuilder.header("X-WNS-Cache-Policy", optional.cachePolicy);
 			}
-			if (!emptyString(optional.requestForStatus)) {
+			if (optional.requestForStatus != WnsRequestForStatusTypeEnum.DEFAULT) {
 				webResourceBuilder.header("X-WNS-RequestForStatus", optional.requestForStatus);
 			}
 			if (!emptyString(optional.tag)) {
diff --git a/src/main/java/ar/com/fernandospr/wns/model/WnsNotificationRequestOptional.java b/src/main/java/ar/com/fernandospr/wns/model/WnsNotificationRequestOptional.java
index 727f55f..034a73e 100644
--- a/src/main/java/ar/com/fernandospr/wns/model/WnsNotificationRequestOptional.java
+++ b/src/main/java/ar/com/fernandospr/wns/model/WnsNotificationRequestOptional.java
@@ -1,20 +1,25 @@
 package ar.com.fernandospr.wns.model;
 
+import ar.com.fernandospr.wns.model.types.WnsCachePolicyTypeEnum;
+import ar.com.fernandospr.wns.model.types.WnsRequestForStatusTypeEnum;
+
 /**
  * Optional headers from <a href="http://msdn.microsoft.com/en-us/library/windows/apps/hh465435.aspx#send_notification_request">http://msdn.microsoft.com/en-us/library/windows/apps/hh465435.aspx#send_notification_request</a>
  */
 public class WnsNotificationRequestOptional {
 	/**
-	 * Should be any of {@link ar.com.fernandospr.wns.model.types.WnsCachePolicyType}
+	 * Should be any of {@link ar.com.fernandospr.wns.model.types.WnsCachePolicyTypeEnum}
 	 */
-	public String cachePolicy;
+	public WnsCachePolicyTypeEnum cachePolicy;
 	
 	/**
-	 * Should be any of {@link ar.com.fernandospr.wns.model.types.WnsRequestForStatusType}
+	 * Should be any of {@link ar.com.fernandospr.wns.model.types.WnsRequestForStatusTypeEnum}
 	 */
-	public String requestForStatus;
+	public WnsRequestForStatusTypeEnum requestForStatus;
 	
 	public String tag;
 	
 	public String ttl;
+	
+	
 }
diff --git a/src/main/java/ar/com/fernandospr/wns/model/types/WnsRequestForStatusType.java b/src/main/java/ar/com/fernandospr/wns/model/types/WnsCachePolicyTypeEnum.java
similarity index 50%
rename from src/main/java/ar/com/fernandospr/wns/model/types/WnsRequestForStatusType.java
rename to src/main/java/ar/com/fernandospr/wns/model/types/WnsCachePolicyTypeEnum.java
index 7aee23e..f4ebae9 100644
--- a/src/main/java/ar/com/fernandospr/wns/model/types/WnsRequestForStatusType.java
+++ b/src/main/java/ar/com/fernandospr/wns/model/types/WnsCachePolicyTypeEnum.java
@@ -3,7 +3,19 @@
 /**
  * From <a href="http://msdn.microsoft.com/en-us/library/windows/apps/hh465435.aspx#send_notification_request">http://msdn.microsoft.com/en-us/library/windows/apps/hh465435.aspx#send_notification_request</a>
  */
-public final class WnsRequestForStatusType {
-	public static final String TRUE = "true";
-	public static final String FALSE = "false";
-}
+public enum WnsCachePolicyTypeEnum{
+	DEFAULT(0, ""),
+	CACHE(1,"cache"),
+	NOCACHE(2,"no-cache")
+	;
+
+	private int type;
+	private String label;
+	
+	private WnsCachePolicyTypeEnum(int type, String label)
+	{
+	    this.type = type;
+	    this.label = label;
+	}
+
+}
\ No newline at end of file
diff --git a/src/main/java/ar/com/fernandospr/wns/model/types/WnsCachePolicyType.java b/src/main/java/ar/com/fernandospr/wns/model/types/WnsRequestForStatusTypeEnum.java
similarity index 51%
rename from src/main/java/ar/com/fernandospr/wns/model/types/WnsCachePolicyType.java
rename to src/main/java/ar/com/fernandospr/wns/model/types/WnsRequestForStatusTypeEnum.java
index b29688d..12189a3 100644
--- a/src/main/java/ar/com/fernandospr/wns/model/types/WnsCachePolicyType.java
+++ b/src/main/java/ar/com/fernandospr/wns/model/types/WnsRequestForStatusTypeEnum.java
@@ -3,7 +3,18 @@
 /**
  * From <a href="http://msdn.microsoft.com/en-us/library/windows/apps/hh465435.aspx#send_notification_request">http://msdn.microsoft.com/en-us/library/windows/apps/hh465435.aspx#send_notification_request</a>
  */
-public final class WnsCachePolicyType {
-	public static final String CACHE = "cache";
-	public static final String NOCACHE = "no-cache";
+public enum WnsRequestForStatusTypeEnum {
+	DEFAULT(0,""),
+	TRUE(1,"true"),
+	FALSE(2,"false")
+	;
+	
+	private int type;
+	private String label;
+	private WnsRequestForStatusTypeEnum(int type, String label)
+	{
+		this.type = type;
+		this.label = label;
+	}
+	
 }