DOM Level 3

The third level of the DOM specification is just additional development of Level 2. It has all the features of its predecessors—some of them modified—plus further enhancement. At the time of this writing, the specification had an official status of the Working Draft. Further changes are still possible.

Level 3 adds the following features to the DOM API:

• Abstract Schemas and Load and Save— These modules provide object models for accessing the XML abstract schemas, such as DTDs and XML Namespaces and loading/saving DOM representations from/to XML files. The Abstract Schemas module comprises two sets of interfaces: a set for editing documents and a set for editing abstract schemas. To determine which of the sets is supported by an implementation, you can call the hasFeature() method with a parameter "AS-DOC" for the first set and "AS-EDIT" for the latter one. The "LS" feature name stands for the Load and Save module.

• Events (enhancement of Level 2)— The Events module (the feature name is “Events”) builds on the same module of Level 2 providing additional features and some changes to the Level 2 interfaces. The specification focuses on providing a flexible event model for working with DOM documents—keeping in mind the need for a high degree of backward compatibility with old HTML event models provided with IE 3.0 and Netscape 3.0 browsers. The following features can be optionally included into implementations: UIEvents, MouseEvents, TextEvents, MutationEvents, and HTMLEvents.

• XPath— This module (XPath is the feature name) enables DOM applications to locate nodes using the XPath expressions. An important point is that the specification focuses on different compatibility issues between the XPath and DOM and defines interfaces that are free from compatability problems.