diff -u -r1.1 -r1.2
--- HPSEcal3.java	24 Aug 2011 22:10:16 -0000	1.1
+++ HPSEcal3.java	29 Aug 2011 23:06:07 -0000	1.2
@@ -5,6 +5,9 @@

 import static java.lang.Math.sin;
 import static java.lang.Math.tan;
 

+import java.util.ArrayList;
+import java.util.List;
+

 import org.jdom.Element;
 import org.jdom.JDOMException;
 import org.lcsim.geometry.compact.converter.lcdd.util.Box;

@@ -20,27 +23,41 @@

 /**
  * LCDD model for the HPS inner ECal.
  * 

- * Coordinate System Notes:

+ * Coordinate System defined as follows:

  * 

- * Beam travels in +X direction.
- * Magnetic field is -Z.
- * Y is the beam bend plane.

+ * <ul>
+ * <li>Beam travels in +X direction.</li>
+ * <li>Magnetic field is in -Z.</li>
+ * <li>Y is the beam bend plane.</li>
+ * </ul>

  * 

- * The dimensions element defines the crystal HALF dimensions: x1, x2, y1, y2, and z.

+ * The <dimensions> element defines the crystal HALF dimensions: x1, x2, y1, y2, and z.

  * 

- * The layout element defines the placement of the crystals.

+ * The <layout> element defines the placement of the crystals.

  * 
  * <ul>

- * <li>beamgap - offset from the beamline in the Y coordinate</li>

+ * <li>beamgap - offset from the beamline in the Y coordinate of the top and bottom halves</li>

  * <li>nx - number of crystals in X</li>
  * <li>ny - number of crystals in Y along each side of beam</li>

- * <li>dface - distance from origin to the face of the calorimeter along X</li>

+ * <li>dface - distance from origin to the face of the calorimeter along Z</li>

  * </ul>
  * 

+ * Under the layout element, <remove> tags can be included to exclude
+ * crystal placement by range.  This element has the following parameters.
+ * 
+ * <ul>
+ * <li>ixmin - minimum x index to exclude (inclusive)</li>
+ * <li>ixmax - maximum x index to exclude (inclusive)</li>
+ * <li>iymin - minimum y index to exclude (inclusive)</li>
+ * <li>iymax - maximum y index to exclude (inclusive)</li>
+ * </ul> 
+ * 
+ * To be excluded, a crystal's ID must pass all four of these min/max checks.
+ * 

  * @author Jeremy McCormick
  * @author Tim Nelson
  * 

- * @version $Id: HPSEcal3.java,v 1.1 2011/08/24 22:10:16 jeremy Exp $

+ * @version $Id: HPSEcal3.java,v 1.2 2011/08/29 23:06:07 jeremy Exp $

  */
 public class HPSEcal3 extends LCDDSubdetector
 {

@@ -53,6 +70,73 @@

     // Margin for mother volume.
     static final double margin = 1.1;
     

+    List<CrystalRange> ranges = new ArrayList<CrystalRange>();
+    
+    private static class CrystalRange
+    {
+        int ixmin;
+        int ixmax;
+        int iymin;
+        int iymax;
+                                              
+        CrystalRange(Element elem) throws Exception
+        {
+            ixmin = ixmax = iymin = iymax = 0;
+                                    
+            if (elem.getAttribute("ixmin") != null)
+            {
+                ixmin = elem.getAttribute("ixmin").getIntValue();                
+            }
+            else               
+            {
+                throw new RuntimeException("Missing ixmin parameter.");
+            }
+            
+            if (elem.getAttribute("ixmax") != null)
+            {
+                ixmax = elem.getAttribute("ixmax").getIntValue();
+            }
+            else               
+            {
+                throw new RuntimeException("Missing ixmax parameter.");
+            }
+            
+            if (elem.getAttribute("iymin") != null)
+            {
+                iymin = elem.getAttribute("iymin").getIntValue();
+            }
+            else               
+            {
+                throw new RuntimeException("Missing ixmax parameter.");
+            }
+            
+            if (elem.getAttribute("iymax") != null)
+            {
+                iymax = elem.getAttribute("iymax").getIntValue();
+            }
+            else
+            {
+                throw new RuntimeException("Missing iymax parameter.");
+            }                                   
+        }
+    }
+    
+    private boolean checkRange(int ix, int iy, List<CrystalRange> ranges)
+    {
+        if (ranges.size() == 0)
+            return true;
+        for (CrystalRange range : ranges)
+        {
+            if ((ix >= range.ixmin && ix <= range.ixmax) 
+                    && ((iy >= range.iymin) && (iy <= range.iymax)))
+            {
+                return false;
+            }
+            
+        }
+        return true;
+    }
+    

     HPSEcal3(Element node) throws JDOMException
     {
         super(node); 

@@ -61,7 +145,7 @@

     void addToLCDD(LCDD lcdd, SensitiveDetector sens) throws JDOMException
     {
         if (sens == null)

-            throw new RuntimeException("SensitiveDetector is null!");

+            throw new RuntimeException("SensitiveDetector parameter points to null.");

         
         // Crystal dimensions.
         Element dimensions = node.getChild("dimensions");

@@ -81,6 +165,20 @@

         int nx = layout.getAttribute("nx").getIntValue();
         int ny = layout.getAttribute("ny").getIntValue();
         double dface = layout.getAttribute("dface").getDoubleValue();

+        
+        // Setup range of indices to be skipped.
+        for (Object obj : layout.getChildren("remove"))
+        {
+            Element remove = (Element)obj;
+            try 
+            {
+                ranges.add(new CrystalRange(remove));
+            }
+            catch (Exception x)
+            {
+                throw new RuntimeException(x);
+            }
+        }

                 
         // Setup crystal logical volume.
         Trapezoid crystalTrap = new Trapezoid("crystal_trap", dx1, dx2, dy1, dy2, dz);

@@ -169,7 +267,7 @@

                 }
                 
                 // Set parameters for next crystal placement.

-                // FIXME Need documentation here.