Adding accessibility supported explanation

explainer/index.html

@@ -417,7 +417,26 @@ <h3>Additional Concepts</h3>
                 <li>Pre-assessment checks: Pre-Assessment checks are tests or criteria that implementers can use to determine if they are ready to
                     assess conformance. The intent of specifying these would be to help implementers prepare for conformance
                     testing, not to create a new level of conformance. </li>
-            </ul>   
+            </ul>  
+        <section id="accessibility-supported">
+            <h3>Only accessibility-supported ways of using technologies</h3>
+
+            <p>The concept of "accessibility-supported" is to account for the variety of user-agents and scenarios. How does an author know that a particular technique for meeting a guideline will work in practice with user-agents that are used by real people?</p>
+
+            <p>The intent is for the responsibility of testing with user-agents to vary depending on the level of conformance.</p> 
+
+            <p>At the foundational level of conformance assumptions can be made by authors that methods and techniques provided by WCAG 3 work. At higher levels of conformance the author may need to test that a technique works, or check that available user-agents meet the requirement, or a combination of both.</p>
+
+            <p>This approach means the working group will ensure that methods and techniques included do have reasonably wide and international support from user-agents, and there are sufficient techniques to meet each outcome.</p>
+
+            <p>The intent is that WCAG 3 will use a content-management-system to support tagging of methods/techniques with support information. There should also be a process where interested parties can provide information.</p>
+
+            <p>An "accessibility support set" is used at higher levels of conformance to define which user-agents and assistive technologies you test with. It would be included in a conformance claim, and enables authors to use techniques that are not provided with WCAG 3.</p>
+
+            <p>An exception for long-present bugs in assistive technology is still under discussion.</p>
+
+        </section>
+
     </section>
 
     <section id="schedule">