NetDataContractSerializer and CLR types
List<string> list = new List<string>();
list.Add("joe");
list.Add("sam");

NetDataContractSerializer ser = new NetDataContractSerializer();
using (FileStream stream = File.OpenWrite("test.xml"))
{
    ser.Serialize(stream, list);
}

<ArrayOfstring z:Id="1" z:Type="System.Collections.Generic.List`1[[System.String, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]]" z:Assembly="0" xmlns="http://schemas.microsoft.com/2003/10/Serialization/Arrays" xmlns:i="http://www.w3.org/2001/XMLSchema-instance" xmlns:z="http://schemas.microsoft.com/2003/10/Serialization/"><_items z:Id="2" z:Size="4"><string z:Id="3">joe</string><string z:Id="4">sam</string><string i:nil="true"/><string i:nil="true"/></_items><_size>2</_size><_version>2</_version></ArrayOfstring>

<ArrayOfstring z:Id="1" z:Type="System.Collections.Generic.List`1[[System.String, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]]" z:Assembly="0" xmlns="http://schemas.microsoft.com/2003/10/Serialization/Arrays" xmlns:i="http://www.w3.org/2001/XMLSchema-instance" xmlns:z="http://schemas.microsoft.com/2003/10/Serialization/"><_items z:Id="2" z:Size="4"><string z:Id="3">joe</string><string z:Id="4">sam</string><string i:nil="true"/><string i:nil="true"/></_items><_size>2</_size><_version>2</_version></ArrayOfstring>