diff --git a/guidelines/terms/20/contrast-ratio.html b/guidelines/terms/20/contrast-ratio.html
index eee5a807ce..c52a117c1d 100644
--- a/guidelines/terms/20/contrast-ratio.html
+++ b/guidelines/terms/20/contrast-ratio.html
@@ -15,20 +15,20 @@
    
    <p class="note">Contrast ratios can range from 1 to 21 (commonly written 1:1 to 21:1).</p>
    
-   <p class="note">Because authors do not have control over user settings as to how text is rendered
-      (for example font smoothing or anti-aliasing), the contrast ratio for text can be
+   <p class="note">Because authors do not have control over user settings as to how text and non-text content is rendered
+      (for example font smoothing or anti-aliasing), the contrast ratio can be
       evaluated with anti-aliasing turned off.
    </p>
    
    <p class="note">For the purpose of Success Criteria 1.4.3 and 1.4.6, contrast is measured with respect
-      to the specified background over which the text is rendered in normal usage. If no
-      background color is specified, then white is assumed.
+      to the specified background over which the content is rendered in normal usage. If no
+      background color is specified, then white is assumed. If no
+      foreground color is specified, then black is assumed.
    </p>
    
-   <p class="note">Background color is the specified color of content over which the text is to be rendered
-      in normal usage. It is a failure if no background color is specified when the text
+   <p class="note">It is a failure if no background color is specified when the foreground
       color is specified, because the user's default background color is unknown and cannot
-      be evaluated for sufficient contrast. For the same reason, it is a failure if no text
+      be evaluated for sufficient contrast. For the same reason, it is a failure if no foreground
       color is specified when a background color is specified.
    </p>
    
diff --git a/techniques/aria/ARIA19.html b/techniques/aria/ARIA19.html
index dc14771408..9dc27cc6a3 100644
--- a/techniques/aria/ARIA19.html
+++ b/techniques/aria/ARIA19.html
@@ -3,7 +3,7 @@
    </section><section id="description"><h2>Description</h2>
       <p>The purpose of this technique is to notify Assistive Technologies (AT) when an input error occurs. The <code class="att">aria-live</code> attribute makes it possible for an AT (such as a screen reader) to be notified when error messages are injected into a Live Region container. The content within the <code class="att">aria-live</code> region is automatically read by the AT, without the AT having to focus on the place where the text is displayed.
 </p>
-      <p>There are also a number of <a href="https://www.w3.org/WAI/PF/aria-practices/#chobet">special case live region roles</a> which can be used instead of applying live region properties directly.</p>
+      <p>There are also a number of <a href="https://www.w3.org/TR/wai-aria-1.1/#live_region_roles">special case live region roles</a> which can be used instead of applying live region properties directly.</p>
    </section><section id="examples"><h2>Examples</h2>
       <section class="example">
          <h3>Injecting error messages into a container with role=alert already present in the DOM</h3>
@@ -95,4 +95,4 @@ <h3>Injecting error messages into a container with role=alert already present in
                </li>
          </ul>
       
-   </section></body></html>
\ No newline at end of file
+   </section></body></html>
diff --git a/understanding/20/on-input.html b/understanding/20/on-input.html
index 41f5a1c08c..aa852cbcc3 100644
--- a/understanding/20/on-input.html
+++ b/understanding/20/on-input.html
@@ -42,6 +42,21 @@ <h2>Intent of On Input</h2>
          
       </div>
       
+	  <div class="note">
+
+         <p>If the user interface component is not fully operable with the keyboard due to the <a class="glossary">change of context</a>, 
+		    this would be a violation of SC 2.1.1.
+         </p>
+
+      </div>
+
+      <div class="note">
+
+         <p>A <a class="glossary">change of context</a> should only be made if this makes further operation of the application easier. 
+		 If the change of context makes the operation difficult for impaired people, it is recommended to avoid the context change. 
+         </p>
+
+      </div>
       
    </section>
    <section id="benefits">