[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]
When overridden in a derived class, writes the XML declaration with the version "1.0".
Assembly: System.Xml (in System.Xml.dll)
This is not the first write method called after the constructor.
The encoding level of the document is determined by how the writer is implemented. When WriteStartDocument is called the writer validates that what you are writing is a well-formed XML document. For example, it checks that the XML declaration is the first node, that one and only one root-level element exists, and so on. If this method is not called, the writer assumes an XML fragment is being written and applies no root level rules.
If WriteStartDocument has been called and then the WriteProcessingInstruction method is used to create another XML declaration, an exception will be thrown.