Writes an XML element that contains a string as the body. System.Xml.XmlWriter inserts an xsi:nil='true' attribute if the string's value is null.
The protected members of System.Xml.Serialization.XmlSerializationWriter are intended for use only by derived classes that are used internally within the .NET Framework XML serialization infrastructure.
When set to true, the nil attribute from the XML Schema instance namespace (abbreviated xsi) indicates a null value.
The XmlSerializationWriter.WriteNullableStringEncodedRaw(string, string, string, System.Xml.XmlQualifiedName) method is called only when writing SOAP-encoded XML, as described in Section 5 of the SOAP 1.1 specification.