How can I add a key to a element?

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I write an element in an XML file using XmlWriter\[code\]using (XmlWriter writer = XmlWriter.Create("test.x)){ writer.WriteStartElement("Order"); writer.WriteEndElement();}\[/code\]which writes the following to the file\[code\]<Order></Order>\[/code\]However, I want to write the following\[code\]<Order key="Name"></Order>\[/code\]WriteStartElement only takes one argument:\[code\]public void WriteStartElement(string localName)\[/code\]So I guess I have to use a different function, but I can't find which one. So ho can I add a key to an element?