diff --git a/help/en/html/tools/scripting/WhatWhere.shtml b/help/en/html/tools/scripting/WhatWhere.shtml
index d6d84d0250d..5d51e3be99e 100644
--- a/help/en/html/tools/scripting/WhatWhere.shtml
+++ b/help/en/html/tools/scripting/WhatWhere.shtml
@@ -29,6 +29,8 @@
       <!-- Page Body -->
 
       <h1>JMRI: "What...Where" of Jython Scripting with JMRI</h1>
+ 	  <!-- Page reorganized by Jerry Grochow 2018-11-29 -->
+
 
       <p class="subtitle">Other interesting tidbits about
       scripting in JMRI with Jython</p>
@@ -36,7 +38,9 @@
       <ul>
       <li><a href="#storescripts">Where should I store my JMRI Jython scripts?</a></li>
       <li><a href="#classes">Where can I find more information on the JMRI classes?</a></li>
+      <li><a href="#names">What is the difference between System names and User names?</a></li>     
 	  <li><a href="#import">What do the words "<code>import</code>" and "<code>class</code>" mean?</a></li>
+      <li><a href="#threads">Why should I based my script on "Siglet" and "AbstractAutomaton" classes?</a></li>
       <li><a href="#siglet-automaton">What's the difference between the "Siglet" and
       "AbstractAutomaton" classes?</a></li>
 	  </ul>
@@ -48,7 +52,8 @@
       <p>See also <a href="Python.shtml">Jython/Python Language</a> for general info about the language.</p>
 	  
 	  
-            
+ <!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->	  
+           
 	  <h2><a id="storescripts">Where should I store my JMRI Jython scripts?</a></h2>
       
       <div class="para">
@@ -68,6 +73,7 @@
       <p><a href="#WhatWhereTopOfPage">[Go to top of page]</a></p>
       </div>
       
+  <!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->	  
       
       <h2><a id="classes">Where can I find more information on the JMRI classes?</a></h2>
 
@@ -100,9 +106,43 @@
 
         </div>
 
-	  
-	      <h2><a id="import">What do the words "<code>import</code>",
-      "<code>class</code>" mean?</a></h2>
+  <!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->	  	
+     <h2><a id="names">What is the difference between System Names and User Names?</a></h2>
+
+      <p>Click for more information on <a href="../../../../../help/en/html/doc/Technical/Names.shtml"> Names and Naming</a>.</p>
+		
+		<p>System names for sensors, turnouts, lights and others, are connection specific. A LocoNet sensor
+		name begins with "LS" while a CMRI sensor begins with "CS" and an internal sensor with "IS". 
+		"provide" methods check the prefix of the passed string to determine if it matches a defined connection
+		or internal. If so, and the rest of the name is valid, the sensor is created. If a match does not 
+		exist, it assigns the prefix for the first connection in the currently open connection list.</p>
+		
+		<p>Example: If your connections are LocoNet and CMRI, a provideSensor request without a prefix of LS, 
+		CS or IS, will be assigned LS. If the name value is not one to four numeric digits (a LocoNet 
+		requirement), you get a bad format error. Memories are only internal, so provideMemory uses "IM" as 
+		the default prefix.</p>
+        
+        <p>Since System names follow a prescribed format, there is a procedure for checking whether a name
+        is valid.  Use this code to create a sensor with a valid name:</p>
+        
+        <!-- Example adapted from Randall Wood post to jmriusers@groups.io 2019-09-06 -->
+        <pre>
+        try:
+           sensors.validateSystemNameFormat(MySensorSystemName)
+        except jmri.NamedBean.BadSystemNameException:
+           print 'Invalid name: ', MySensorSystemName 
+        </pre>    
+		
+		<p>User names are set after input and outputs are created. They can be any character string you want. 
+		You can use user name or system name in scripts and Logix. The use of user names is recommended for 
+		these purposes if there is the possibility that you will be changing your control system in which case 
+		system names will be changing as well.</p>
+        
+     <p><a href="#WhatWhereTopOfPage">[Go to top of page]</a></p>        
+
+
+  <!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->	  	    
+	   <h2><a id="import">What do the words "<code>import</code>", "<code>class</code>" mean?</a></h2>
 
       <div class="para">
         They're part of the jython language used for the scripting.
@@ -147,14 +187,33 @@
 
         </div>
 	  
-     
+    <!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->	  
+      <h2><a id="threads">Why should I base my scripts on "Siglet" and "AbstractAutomaton" classes?</a></h2>
+ 	  <!-- Section created by Jerry Grochow 2019-10-14 based on post to jmriusers@groups.io by Bob Jacobson 2018-11-01 -->
+
+      
+      <div class="para">
+      
+      <p>Scripts are part of the main JMRI program. This creates a bit of a problem:  when something goes wrong
+      in a script, it may crash JMRI.  When a script goes to sleep, the whole program sleeps. However, if you want
+      to run independent of JMRI, you can via a separate "thread."  The Siglet and AbstractAutomaton classes have
+      created to allow you to base your scripts on a class that will run as an independent thread but with the 
+      ability to communicate with the rest of JMRI.  For more information, see 
+      <a href="../../../../../help/en/html/doc/Technical/Threads.shtml">the section on threads.</a></p>      
+      
+      <p>Effectively, each Automat or Siglet is a separate program running when it needs to.  Since they run in 
+      separate threads, they can wait for something to happen while the rest of the JMRI program proceeds - a
+      very useful capability indeed. </p>    
+      
+      </div>
+  
+  
+    <!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->	  
 	  <h2><a id="siglet-automaton">What's the difference between the "Siglet" and
       "AbstractAutomaton" classes?</a></h2>
 
       <div class="para">
-        (Maybe not a <em>frequently</em> asked question, but it
-        needs to go somewhere)
-
+ 
         <p>Some examples use the <a href=
         "http://jmri.org/JavaDoc/doc/jmri/jmrit/automat/AbstractAutomaton.html" target="_blank">
         AbstractAutomaton</a> class as a base, while others use the
@@ -224,6 +283,7 @@
 
         </div>
 
+  <!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->	  
 	  
 
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