This package is independent of the SAX2 core, though the functionality exposed generally needs to be implemented within a parser core. That independence has several consequences:

• SAX2 drivers are not required to recognize these handlers.
• You cannot assume that the class files will be present in every SAX2 installation.
• This package may be updated independently of SAX2 (i.e. new handlers and classes may be added without updating SAX2 itself).
• The new handlers are not implemented by the SAX2 org.xml.sax.helpers.DefaultHandler or org.xml.sax.helpers.XMLFilterImpl classes. You can subclass these if you need such behavior, or use the helper classes found here.
• The handlers need to be registered differently than core SAX2 handlers.

This package, SAX2-ext, is a standardized extension to SAX2. It is designed both to allow SAX parsers to pass certain types of information to applications, and to serve as a simple model for other SAX2 parser extension packages. Not all such extension packages should need to be recognized directly by parsers, however. As an example, most validation systems can be cleanly layered on top of parsers supporting the standardized SAX2 interfaces.