diff --git a/main/src/com/google/gridworks/expr/functions/arrays/Uniques.java b/main/src/com/google/gridworks/expr/functions/arrays/Uniques.java
new file mode 100644
index 000000000..cc14fb2b9
--- /dev/null
+++ b/main/src/com/google/gridworks/expr/functions/arrays/Uniques.java
@@ -0,0 +1,63 @@
+package com.google.gridworks.expr.functions.arrays;
+
+import java.util.HashSet;
+import java.util.List;
+import java.util.Properties;
+import java.util.Set;
+
+import org.json.JSONArray;
+import org.json.JSONException;
+import org.json.JSONWriter;
+
+import com.google.gridworks.expr.EvalError;
+import com.google.gridworks.expr.ExpressionUtils;
+import com.google.gridworks.gel.ControlFunctionRegistry;
+import com.google.gridworks.gel.Function;
+import com.google.gridworks.util.JSONUtilities;
+
+public class Uniques implements Function {
+
+    public Object call(Properties bindings, Object[] args) {
+        if (args.length == 1) {
+            Object v = args[0];
+            
+            if (v != null) {
+                if (v instanceof JSONArray) {
+                    try {
+                        v = JSONUtilities.toArray((JSONArray) v);
+                    } catch (JSONException e) {
+                        return new EvalError(ControlFunctionRegistry.getFunctionName(this) +
+                                " fails to process a JSON array: " + e.getMessage());
+                    }
+                }
+                
+                if (v.getClass().isArray() || v instanceof List<?>) {
+                    Set<Object> set = null;
+                    
+                    if (v.getClass().isArray()) {
+                        Object[] a = (Object[]) v;
+                        
+                        set = new HashSet<Object>(a.length);
+                        for (int i = 0; i < a.length; i++) {
+                            set.add(a[i]);
+                        }
+                    } else {
+                        set = new HashSet<Object>(ExpressionUtils.toObjectList(v));
+                    }
+                    return set.toArray();
+                }
+            }
+        }
+        return new EvalError(ControlFunctionRegistry.getFunctionName(this) + " expects an array");
+    }
+
+    public void write(JSONWriter writer, Properties options)
+        throws JSONException {
+    
+        writer.object();
+        writer.key("description"); writer.value("Returns array a with duplicates removed");
+        writer.key("params"); writer.value("array a");
+        writer.key("returns"); writer.value("array");
+        writer.endObject();
+    }
+}
diff --git a/main/src/com/google/gridworks/gel/ControlFunctionRegistry.java b/main/src/com/google/gridworks/gel/ControlFunctionRegistry.java
index 8e83098bc..cf50eabd7 100644
--- a/main/src/com/google/gridworks/gel/ControlFunctionRegistry.java
+++ b/main/src/com/google/gridworks/gel/ControlFunctionRegistry.java
@@ -19,6 +19,7 @@ import com.google.gridworks.expr.functions.Type;
 import com.google.gridworks.expr.functions.arrays.Join;
 import com.google.gridworks.expr.functions.arrays.Reverse;
 import com.google.gridworks.expr.functions.arrays.Sort;
+import com.google.gridworks.expr.functions.arrays.Uniques;
 import com.google.gridworks.expr.functions.booleans.And;
 import com.google.gridworks.expr.functions.booleans.Not;
 import com.google.gridworks.expr.functions.booleans.Or;
@@ -171,6 +172,7 @@ public class ControlFunctionRegistry {
         registerFunction("join", new Join());
         registerFunction("reverse", new Reverse());
         registerFunction("sort", new Sort());
+        registerFunction("uniques", new Uniques());
 
         registerFunction("now", new Now());
         registerFunction("inc", new Inc());
diff --git a/main/src/com/google/gridworks/operations/OperationRegistry.java b/main/src/com/google/gridworks/operations/OperationRegistry.java
index 001eb219d..e661bc0b5 100644
--- a/main/src/com/google/gridworks/operations/OperationRegistry.java
+++ b/main/src/com/google/gridworks/operations/OperationRegistry.java
@@ -8,6 +8,7 @@ import org.json.JSONObject;
 
 import com.google.gridworks.model.AbstractOperation;
 import com.google.gridworks.model.Project;
+import com.google.gridworks.operations.cell.BlankDownOperation;
 import com.google.gridworks.operations.cell.FillDownOperation;
 import com.google.gridworks.operations.cell.MassEditOperation;
 import com.google.gridworks.operations.cell.MultiValuedCellJoinOperation;
@@ -55,6 +56,7 @@ public abstract class OperationRegistry {
         register("multivalued-cell-join", MultiValuedCellJoinOperation.class);
         register("multivalued-cell-split", MultiValuedCellSplitOperation.class);
         register("fill-down", FillDownOperation.class);
+        register("blank-down", BlankDownOperation.class);
         register("transpose-columns-into-rows", TransposeColumnsIntoRowsOperation.class);
         register("transpose-rows-into-columns", TransposeRowsIntoColumnsOperation.class);