The XML | Insert | DOCTYPE command is available in the Grid View of an XML file when a top-level node is selected. It appends a DOCTYPE declaration at the top of the XML document. You must enter the name of the DOCTYPE, and this name must be the same as the name of the document element.
After you have entered the name of the DOCTYPE, you can enter the declarations you wish to use in the internal DTD subset.
•A DOCTYPE declaration may only appear between the XML declaration and the XML document element.
•You could use the Assign DTD command instead to create a DOCTYPE statement that refers to an external DTD document.