diff -u -r1.6 -r1.7
--- SiSensor.java	18 May 2007 21:56:34 -0000	1.6
+++ SiSensor.java	18 May 2007 23:45:11 -0000	1.7
@@ -23,6 +23,8 @@

 import org.lcsim.detector.Rotation3D;
 import org.lcsim.detector.converter.compact.DeDetector;
 import org.lcsim.detector.converter.compact.DeSubdetector;

+import org.lcsim.detector.identifier.IExpandedIdentifier;
+import org.lcsim.detector.identifier.IIdentifier;

 import org.lcsim.detector.identifier.IIdentifierHelper;
 import org.lcsim.detector.solids.Box;
 

@@ -506,6 +508,23 @@

         }
         return subdet.get(0).getIdentifierHelper();
     }

+    
+    /**
+     * Make an {@link IIdentifier} for a given strip number and side number.
+     * 
+     * @author Jeremy McCormick
+     * @param stripNumber The strip number, which should be from 1 to nstrips-1.
+     * @param sideNumber  The side number, which should be 1 or -1.
+     * @return A 64-bit   Identifier for the strip.
+     */
+    public IIdentifier makeStripId( int stripNumber, int sideNumber )
+    {
+        IIdentifierHelper helper = getIdentifierHelper();
+        IExpandedIdentifier id = helper.unpack( getIdentifier(), 0, helper.getIdentifierDictionary().getFieldIndex("side") - 1);
+        id.addValue(sideNumber);
+        id.addValue(stripNumber);
+        return helper.pack( id );
+    }