diff -u -r1.13 -r1.14
--- SIOSimTrackerHit.java	15 May 2008 01:14:00 -0000	1.13
+++ SIOSimTrackerHit.java	15 May 2008 02:18:40 -0000	1.14
@@ -13,7 +13,7 @@

 
 /**
  * @author Tony Johnson

- * @version $Id: SIOSimTrackerHit.java,v 1.13 2008/05/15 01:14:00 jeremy Exp $

+ * @version $Id: SIOSimTrackerHit.java,v 1.14 2008/05/15 02:18:40 jeremy Exp $

  */
 class SIOSimTrackerHit extends BaseSimTrackerHit
 {    

@@ -45,7 +45,7 @@

     public MCParticle getMCParticle()
     {
         if (mcparticle == null) 

-        {

+        { // Check if this has been cached already.

             if (particleref instanceof SIORef)
             {
                 particleref = ((SIORef) particleref).getObject();

@@ -53,6 +53,7 @@

             }
             else 
             {

+                // Added a throw here.  I think this probably constitutes a fatal error.  --JM

                 throw new RuntimeException("Referenced object is not an MCParticle!");
             }
         }