DOM

 DOM Level 1  This concentrates on the actual core, HTML, and XML document models. It contains functionality for document navigation and manipulation

 DOM Level 2  This includes a style sheet object model, and defines functionality for manipulating the style information attached to a document. It also enables traversals on the document, defines an event model and provides support for XML namespaces

 DOM Level 3  This extends the DOM Level 2 Object Model to enable users and applications to:

•  Access keyboard events. Adding the ability of defining groups of events
• Load and Save interfaces: for loading XML source documents into a DOM representation and for saving a DOM representation as an XML document.
• Support an embedded Document Object Model: Currently, the Web is moving towards documents with mixed markup vocabularies, e.g. SVG fragments can be embedded in an XHTML document. This creates new challenges for the DOM, since it also means that DOM APIs and implementations of the different vocabularies need to work together.
• Adapt to changes to core XML functionality: the DOM is an API to an XML document. As auxiliary functionality to XML 1.0 is developed (namespaces, XML Base), the DOM API should model these changes.
• XPath DOM support: The ability to query a DOM tree using XPath will be also included.