diff --git a/plugins/org.eclipse.dd.dsf.debug.ui/src/org/eclipse/dd/dsf/debug/ui/viewmodel/expression/IExpressionLayoutNode.java b/plugins/org.eclipse.dd.dsf.debug.ui/src/org/eclipse/dd/dsf/debug/ui/viewmodel/expression/IExpressionLayoutNode.java
index ea30c602a42..782ba7784a0 100644
--- a/plugins/org.eclipse.dd.dsf.debug.ui/src/org/eclipse/dd/dsf/debug/ui/viewmodel/expression/IExpressionLayoutNode.java
+++ b/plugins/org.eclipse.dd.dsf.debug.ui/src/org/eclipse/dd/dsf/debug/ui/viewmodel/expression/IExpressionLayoutNode.java
@@ -18,14 +18,38 @@ import org.eclipse.debug.internal.ui.viewers.model.provisional.IChildrenUpdate;
 import org.eclipse.jface.viewers.TreePath;
 
 /**
- * 
+ * Interface for layout nodes that can be used within the expression view.  
+ * The methods of this interface allow the {@link ExpressionManagerLayoutNode} 
+ * to use this layout node to delegate expression parsing to this node, and to 
+ * generate deltas for expressions that are owned by this node.
  */
 @SuppressWarnings("restriction")
 public interface IExpressionLayoutNode extends IVMLayoutNode {
-    int getExpressionLength(String expression);
-    void getElementForExpression(IChildrenUpdate update, String expressionText, IExpression expression);
     
-    int getDeltaFlagsForExpression(String expressionText, Object event); 
+    /**
+     * Returns the length of the portion of the expression that can be parsed 
+     * by this node.    
+     * @param expression String to parse
+     * @return length of the expression recognized by this node.  Length of less than 1
+     * indicates that this node cannot parse this expression.
+     */
+    int getExpressionLength(String expression);
+    
+    /**
+     * Retrieves the element for the given expression.  The node implementing 
+     * this method should parse the expression and set a valid view model 
+     * context (VMC) element in the update provided as an argument.
+     * @param update to fill in with the element.  The tree path in this update 
+     * object may contain elements which are not actually displayed in the viewer.  
+     * These element may have been added to the original path by other expression 
+     * layout nodes that have parsed preceding parts of the expression.  
+     * @param expressionText expression string to parse
+     * @param expression expression object that the returned element should contain 
+     */
+    void getElementForExpression(IChildrenUpdate update, String expressionText, IExpression expression);
+
+    int getDeltaFlagsForExpression(String expressionText, Object event);
+    
     void buildDeltaForExpression(IExpression expression, int elementIdx, String expressionText, Object event, 
                                  VMDelta parentDelta, TreePath path, RequestMonitor rm); 
 }