It may not always be possible for the JAXB Schema compiler to determine all details of the generated Java code from the XML schema alone. Several customizing features are provided for adding information to the compiler's output, and for overriding the compiler's defaults for binding schema definitions to Java classes.

The main reasons for customizing are:

• providing meaningful package names
• overriding the default class name (to avoid name clashes)
• overriding the default names for enum constants
• adding documentation
• associating a specific Java class with an XML Schema built-in type

Customizing can be added inline to the schema, or it can be written on a separate file that is passed to the schema compiler. We'll see these techniques in the succeeding subsections.