Add notes to 2.4.3 understanding

Author: patrickhlauke

understanding/20/focus-order.html

@@ -54,6 +54,29 @@ <h2>Intent of Focus Order</h2>
          Web page. Care should be taken so that the focus order makes sense to both of these
          sets of users and does not appear to either of them to jump around randomly. 
       </p>
+
+      <p>Focus order also does not normatively need to follow the visual presentation of the web page,
+         as long as the order in which elements receive focus is logical, and the hierarchy and relationship
+         of content implied by the visual presentation is preserved. For instance, in a two-column
+         layout, visually the assumption in western left-to-right systems may be that elements in the
+         left-hand column would receive focus first. However, if meaning and operation are not affected,
+         it is not a normative failure if elements in the right-hand column receive focus first.
+         Again, as a best practice, care should be taken to make sure the focus order does not
+         appear random and illogical.
+      </p>
+
+      <div class="note">
+         <p>Normatively, it is not a failure of this success criterion if static/non-interactive content
+            receives focus. Making an element that does not act as an actionable user interface component
+            focusable, or programmatically moving focus to such an element, does not necessarily constitute
+            a failure of this success criterion. Similarly, redundant focusable elements – for instance,
+            having two or more "focus stops" for what may visually appear to be a single user interface
+            component – do not automatically fail this criterion. These situations are only failures if they
+            significantly impede the operation of the content. However, as a best practice, authors should
+            avoid excessive use of focusable elements which cannot be operated or actioned, as well as
+            redundant focus stops, as these are likely to make operation unnecessarily tedious for keyboard users.
+         </p>
+      </div>
 
       <p>For clarity:</p>
 
@@ -62,6 +85,8 @@ <h2>Intent of Focus Order</h2>
          <li>Focusable components need to receive focus in an order that preserves meaning and
             operability only when navigation sequences affect meaning and operability.
          </li>
+
+         <li>Focus order does not need to follow visual presentation or layout.</li>
 
          <li>In those cases where it is required, there may be more than one order that will preserve
             meaning and operability.
@@ -70,6 +95,10 @@ <h2>Intent of Focus Order</h2>
          <li>If there is more than one order that preserves meaning and operability, only one of
             them needs to be provided.
          </li>
+
+         <li>Redundant focus stops, and static/non-interactive elements receiving focus, are allowed, as
+            long as they don't significantly impede operation of the content.
+         </li>
 
       </ol>