Attribute types
Besides the description of the structure, a DTD may also contain declarations of attribute types. Attribute types describe the properties of an element type. They are always assigned to an element type.
Simple attribute types and enumeration attribute types can be declared in a DTD.
To define a simple attribute type,
1. place an Attribute type object with the required name in the model and
2. draw a connection from the element type whose property is described by the attribute type to the new attribute type.
3. Then open Attribute Editing to specify further information for the attribute type declaration.
This information includes:
Data type of the attribute value
Attribute default
Default value