Assemblies: System.Xml (in System.Xml.dll)
System.Xml.ReaderWriter (in System.Xml.ReaderWriter.dll)
You must set this value to true when you create a new XmlReader instance if you want to use asynchronous XmlReader methods on that instance. After the XmlReader instance is created, the property is read-only. The default value of this property is false.
This flag is ignored by the XmlReader.Create overload. This means that if you create a new XmlReader based on an existing XmlReader, the async behavior depends on the input XmlReader, and you cannot use the flag to change the async behavior.