Add note about logo/logotypes to 1.4.3, 1.4.6, and 1.4.11 understanding

Author: patrickhlauke

understanding/20/contrast-enhanced.html

@@ -126,7 +126,16 @@ <h2>Intent of Contrast (Enhanced)</h2>
          in charts, graphs, diagrams, and other non-text-based information, which is covered by
          <a href="non-text-contrast">Success Criterion 1.4.11 Non-Text Contrast</a>.         
       </p>
-      
+
+      <div class="note">
+         <p>Although text used as part of a logo or logotype is exempted from contrast requirements,
+            this can be problematic when it also acts as a <em>user interface component</em>
+            (such as a link or other interactive control). In these cases, authors should choose
+            a variant of the logo or logotype that has sufficient contrast.
+            Alternatively, authors should provide an equivalent <em>user interface component</em>
+            which serves the same purpose and does meet the contrast requirements.</p>
+      </div>
+
       <section>
 
          <h3>Rationale for the Ratios Chosen</h3>

understanding/20/contrast-minimum.html

@@ -130,7 +130,16 @@ <h2>Intent of Contrast (Minimum)</h2>
       <p>See also 
          <a href="contrast-enhanced">1.4.6: Contrast (Enhanced)</a>.
       </p>
-      
+
+      <div class="note">
+         <p>Although text used as part of a logo or logotype is exempted from contrast requirements,
+            this can be problematic when it also acts as a <em>user interface component</em>
+            (such as a link or other interactive control). In these cases, authors should choose
+            a variant of the logo or logotype that has sufficient contrast.
+            Alternatively, authors should provide an equivalent <em>user interface component</em>
+            which serves the same purpose and does meet the contrast requirements.</p>
+      </div>
+
       <section>
 
          <h3>Rationale for the Ratios Chosen</h3>

understanding/21/non-text-contrast.html

@@ -396,6 +396,16 @@ <h4>Required for Understanding</h4>
 					<li> The information is available in another form, such as in a table that follows the graph, which becomes visible when a "Long Description" button is pressed.</li>
 					<li> The graphic is part of a logo or brand name (which is considered &quot;essential&quot; to its presentation).</li>
 				</ul>
+
+				<div class="note">
+					<p>Although logos and logotypes are exempted from contrast requirements when they are purely used as
+						<em>graphical objects</em>, this is not the case when they also act as <em>user interface components</em>
+							(such as links or other interactive controls). In these cases, authors should choose
+							a variant of the logo or logotype that has sufficient contrast.
+							Alternatively, authors should provide an equivalent <em>user interface component</em>
+							which serves the same purpose and does meet the contrast requirements.</p>
+				</div>
+
 				</section>
 				<section>
 				<h4>Gradients</h4>