When you use the XmlSerializer class to serialize the XML numeration attribute in the Microsoft .NET Framework 2.0, the XmlSerializer class generates an unexpected result.

For example, you expect the serialization result to be the following: However, the actual result is the following:

Hotfix information

A supported hotfix is now available from Microsoft. However, it is intended to correct only the problem that is described in this article. Apply it only to systems that are experiencing this specific problem. This hotfix may receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next .NET Framework 2.0 service pack that contains this hotfix.

To resolve this problem immediately, contact Microsoft Customer Support Services to obtain the hotfix. For a complete list of Microsoft Customer Support Services telephone numbers and information about support costs, visit the following Microsoft Web site:Note In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

Prerequisites

You must have the .NET Framework 2.0 installed to apply this hotfix.

Restart requirement

You do not have to restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace any other hotfixes.

File information

The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time item in Control Panel.

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

For more information software update terminology, click the following article number to view the article in the Microsoft Knowledge Base:

Steps to reproduce the problem

1. Start Visual Studio 2005.
2. Create a blank C# project by using the following code:

   namespace Test
   {
       class Program
       {
           static void Main(string[] args)
           {
               string outfile = ".\\MyTest.xml";
               myThing mt = new myThing();
               mt.mystring = null;
               mt.ItemElementName = myThing.ItemChoiceType.OptionC;
               mt.item = null;
               mt.itemSpecified = true;
               XmlSerializer ser = new XmlSerializer(typeof(myThing));
               XmlTextWriter wtr = new XmlTextWriter(outfile, Encoding.UTF8);
               ser.Serialize(wtr, mt);
               wtr.Flush();
               wtr.Close();
           }
       }
   
       [XmlRoot(Namespace = "urn:Scott")]
       public class myThing
       {
           [XmlElement("MyString", IsNullable = true)]
           public string mystring;
   
           [XmlChoiceIdentifier("ItemElementName")]
           [XmlElement(ElementName = "OptionA", Type = typeof(object), IsNullable = true)]
           [XmlElement(ElementName = "OptionB", Type = typeof(object), IsNullable = true)]
           [XmlElement(ElementName = "OptionC", Type = typeof(object), IsNullable = true)]
           [XmlElement(ElementName = "OptionD", Type = typeof(object), IsNullable = true)]
           public object item;
   
           [XmlIgnore]
           public bool itemSpecified;
           [XmlIgnore]
           public ItemChoiceType ItemElementName;
           [XmlType(Namespace = "urn:Scott", IncludeInSchema = false, AnonymousType = false)]
           public enum ItemChoiceType
           {
               [XmlEnum("OptionA")]
               OptionA,
               [XmlEnum("OptionB")]
               OptionB,
               [XmlEnum("OptionC")]
               OptionC,
               [XmlEnum("OptionD")]
               OptionD
           }
       }
   }
   

3. Build and run this application.

When you view the MyTest.xml file, you see the problem that the "Symptoms" section describes.