diff --git a/XTChannelArithmetic.py b/XTChannelArithmetic.py
index 0495d92..1a8856f 100755
--- a/XTChannelArithmetic.py
+++ b/XTChannelArithmetic.py
@@ -120,6 +120,12 @@ class ChannelArithmeticDialog(ieb.ImarisExtensionBase):
 
             [4] - ([0]*[3])
 
+    #. Duplicate the second channel (indexes are zero based, so second channel index is 1):
+
+        .. code-block:: Python
+
+            [1]
+
     #. Duplicate all channels:
 
         .. code-block:: Python