The Accessibility Rules Format 1.0 Specification  has been approved by the OpenAjax Alliance Steering Committee as an official Specification of OpenAjax Alliance, and unanimous recommendation of approval by the OpenAjax Alliance membership.
The Rule Format 1.0 spec has been under development within the Accessibility Working Group  for a couple of years (with early work done in task force stage before an official Working Group was formed last year).
Here is a description of the Rules Format 1.0 Specification:
This document describes the requirements for the structure of OpenAjax Accessibility (OAA) Web validation rules and rule sets used by accessibility test tools. Version 1.0 of this rules format will be used to create validation rules for W3C Web Content Accessibility Guidelines 2.0 targeted at HTML 4.X and WAI-ARIA. These rules are targeted at dynamic content and may be applied to a specific Document Object Model (DOM) node or to a set of DOM nodes or the entire document. Rules are to be written in JavaScirpt and rely on the W3C DOM with common browser extensions. Test tools can trigger the evaluation of these rules based on user interaction and external events. To see rule samples, in development, please see  or find the sources in the OAA repository on Source Forge .
Multiple companies/products that have stated publicly that they are implementing parts of this Specification:
* AInspector – the accessibility inspector for Firefox 
* Illinois Functional accessibility evaluator 2.0 
* Accessibility extensions for Firefox 
* IBM Rational Policy Tester
* OpQuast Reporting Tool 
The co-chairs of the Accessibility Working Group (Rich Schwerdtfeger of IBM and Jon Gunderson of University of Illinois) expect that work will continue towards an updated version 2 of this Specification.