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:
Describe a valid XML document
Describe the process for creating a DTD
Declare basic elements in a DTD and specify their content
Write element declarations for mixed content and declare empty elements
Reference DTD declarations in XML
Create a DTD file which works with a separate XML file
Create a DTD from an existing set of tags
In the next lesson, the concept of a valid XML document will be discussed.
An XML document can result from the aggregation of various chunks of data
- schemas, and
coming from different network locations.
In these cases, the BaseURI property tells you where these nodes come from.
If the XML document is being processed through a stream (for example, an in-memory string), no URI is available and the BaseURI property returns the empty string.