When overridden in a derived class, writes out the specified name, ensuring it is a valid NmToken according to the W3C XML 1.0 recommendation (http://www.w3.org/TR/1998/REC-xml-19980210#NT-Name).
Assembly: System.Xml (in System.Xml.dll)
name is not a valid NmToken; or name is either null or String.Empty.
An XmlWriter method was called before a previous asynchronous operation finished. In this case, InvalidOperationException is thrown with the message “An asynchronous operation is already in progress.”