A document type definition (DTD) describes the grammar that can be used in an XML file and indicates the valid arrangement of the file's tags. It can exist as a prologue to an XML file (internal DTD) or as a separate file (external DTD). You can create a new DTD yourself, or you can automatically generate a DTD from an existing XML document.
To generate a DTD from an existing XML file:
The new DTD node appears in the Files window and is displayed in the Source Editor.
To create an empty DTD:
In the Files window, the new DTD node appears under the package you specified. The DTD is also displayed in the Source Editor.