W3C:

2008-11-14: The Web Applications Working Group has published the Last Call Working Draft of Selectors API. Selectors, which are widely used in CSS, are patterns that match against elements in a tree structure. The Selectors API specification defines methods for retrieving Element nodes from the DOM by matching against a group of selectors. It is often desirable to perform DOM operations on a specific set of elements in a document. These methods simplify the process of acquiring specific elements, especially compared with the more verbose techniques defined and used in the past. Comments are welcome through 12 December. Learn more about the Rich Web Client Activity. (Permalink)