diff -N HitNull.java
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ HitNull.java	13 Sep 2007 22:41:25 -0000	1.1
@@ -0,0 +1,97 @@

+//package org.lcsim.recon.tracking.trfbase;
+
+import org.lcsim.recon.tracking.trfbase.ETrack;
+import org.lcsim.recon.tracking.trfbase.Hit;
+import org.lcsim.recon.tracking.trfbase.HitDerivative;
+import org.lcsim.recon.tracking.trfbase.HitError;
+import org.lcsim.recon.tracking.trfbase.HitVector;
+import org.lcsim.recon.tracking.trfutil.Assert;
+
+/**
+ * 
+ * A null hit so that I have a way to add pure
+ * scattering surfaces to HTracks.
+ *
+ *@author $Author: kutschke $
+ *@version $Id: HitNull.java,v 1.1 2007/09/13 22:41:25 kutschke Exp $
+ *
+ * Date $Date: 2007/09/13 22:41:25 $
+ *
+ */
+
+
+public class HitNull extends Hit
+{
+    
+    private static final int SIZE=0;
+    private int _ival;
+            
+    public String toString()
+    {
+	return "Dummy hit prediction " + _ival + "\n"
+	    + "Cluster address: " + _pclus + "\n"
+	    + "Cluster: " + _pclus + "\n";
+    }
+            
+    protected boolean equal(Hit hp)
+    {
+	Assert.assertTrue( hp.type().equals(type()) );
+	// All null hits are equal to each other.
+	return true;
+    }
+            
+    // static methods
+    // Return the type name.
+    public static String typeName()
+    { return "HitNull";
+    }
+
+    // Return the type.
+    public static String staticType()
+    { return typeName();
+    }
+            
+    public HitNull()
+    {
+    }
+            
+    HitNull( HitNull ht)
+    {
+    }
+
+    public String type()
+    { return staticType();
+    }
+    
+    public int size()
+    { return SIZE;
+    };
+
+    public HitVector measuredVector()
+    {
+	return new HitVector();
+    }
+    public HitError measuredError()
+    {
+	return new HitError();
+    }
+    public HitVector predictedVector()
+    {
+	return new HitVector();
+    }
+    public HitError predictedError()
+    {
+	return new HitError();
+    }
+    public HitDerivative dHitdTrack()
+    {
+	return new HitDerivative();
+    }
+    public HitVector differenceVector()
+    { return new HitVector();
+    }
+    public void update(ETrack tre)
+    { 
+    }
+}
+