There are four kinds of content models: element content, mixed content, EMPTY content and ANY content
In the element content content model an element can only contain other child elements. In the mixed content content model, an element can contain both character data (text that is not parsed by the XML parser) and other child elements. In the EMPTY content content model, an element cannot contain any other elements or text. In the ANY content content model, the element can literally contain anything - other elements, in any number, and text.
In the DTD editor, you can create elements with any of these content models. When you create an element in the DTD editor, a child element with an EMPTY content model is automatically created.
The following instructions were written for the Resource perspective, but they will also work in many other perspectives.
To edit an element's content model, follow these steps: