XML documents are valid only if they conform to the structural and syntactical rules of a DTD.
Therefore it is important to know the basics of creating DTDs.
In this module, you will create DTDs for existing XML documents.
You will also use a DTD as a guideline for creating new XML documents that conform to the rules laid out in the DTD.

After completing this module, you will have the skills and knowledge necessary to:

1. Describe a valid XML document
2. Describe the process for creating a DTD
3. Declare basic elements in a DTD and specify their content
4. Write element declarations for mixed content and declare empty elements
5. Reference DTD declarations in XML
6. Create a DTD file which works with a separate XML file
7. Create a DTD from an existing set of tags

In the next lesson, the concept of a valid XML document will be discussed.