diff --git a/Doc/Sda1/jpaintro.xml b/Doc/Sda1/jpaintro.xml
index 48ced4fcdbec4b7bca36d552be82aa8c1582196a..ce707f8610314c7307aa40cc3a595355db209b9a 100644
--- a/Doc/Sda1/jpaintro.xml
+++ b/Doc/Sda1/jpaintro.xml
@@ -41,6 +41,24 @@
     </itemizedlist>
   </figure>
 
+  <figure xml:id="sda1_jpa_Impedance">
+    <title>What about <quote>impedance</quote>?</title>
+
+    <itemizedlist>
+      <listitem>
+        <para>Borrowed from electronics.</para>
+      </listitem>
+
+      <listitem>
+        <para>Combining resistance and inductance.</para>
+      </listitem>
+
+      <listitem>
+        <para>Relevant when coupling subsystems.</para>
+      </listitem>
+    </itemizedlist>
+  </figure>
+
   <figure xml:id="sda1_jpa_OrImpedanceMismatch">
     <title>OR <link
     xlink:href="http://www.agiledata.org/essays/impedanceMismatch.html">impedance
@@ -60,7 +78,7 @@
       </tr>
 
       <tr>
-        <td valign="top">Inheritance / Polymorphism</td>
+        <td valign="top">Inheritance / polymorphism</td>
 
         <td valign="top">-</td>
       </tr>
@@ -84,9 +102,10 @@
       </tr>
 
       <tr>
-        <td valign="top">Type differences e.g. <code>String</code></td>
+        <td valign="top">Type differences e.g.
+        <classname>String</classname></td>
 
-        <td valign="top"><code>char</code>, <code>varchar</code>(...)</td>
+        <td valign="top"><code>CHAR</code>, <code>VARCHAR</code>(...)</td>
       </tr>
     </informaltable>
   </figure>