Each VoiceXML document must have a vxml element as its root node. Figure 3-1 lists the legal children of the vxml element type.
All of these children are other VoiceXML element types except two: event.handler and dialog. These are abstract element types, defined as entities in the DTD. Each of them can represent a union of element types.
Figure 3-2 shows the event.handler element types. Any of these event.handler element types can legally be a child of the vxml element type.
Figure 3-3 shows the definition of the abstract dialog ...