DOM
From MobileRead
The Document Object Model, DOM, is a platform- and language-neutral interface that will allow programs and scripts to dynamically access and update the content, structure and style of documents. The document can be further processed and the results of that processing can be incorporated back into the presented page. There is an overview of DOM-related materials at W3C and around the web.
This is related to DHTML - Dynamic HTML - used in JavaScripts, html menus, etc. to provide a uniform and standard way to access web documents and data.