DTD Statements 

This section describes the syntax for the four types of defining statements available for authoring document type definitions (DTDs).

Definition	Description
ATTLIST (Attribute List)	Declares a list of XML attributes. These attributes are qualified by name, data type, implied default values, and the name of any elements that permit their use.
ELEMENT	Declares an XML element type name and its valid sub-elements ("children").
ENTITY	Declares special character references, text macros (much like a C/C++ #define statement), and other repetitive content from external sources (like a C/C++ #include statement).
NOTATION	Declares external non-XML content (for example, binary image data), and the external application that handles that content.