--- a/src/main/csharp/jp.ac.u-ryukyu.ie.cr/jungle/transaction/DefaultTreeNode.cs	Tue Jul 05 07:20:41 2016 +0900
+++ b/src/main/csharp/jp.ac.u-ryukyu.ie.cr/jungle/transaction/DefaultTreeNode.cs	Tue Jul 19 16:47:43 2016 +0900
@@ -1,17 +1,17 @@
 using UnityEngine;
 public class DefaultTreeNode : TreeNode {
 	private List<TreeNode> children;
-	private TreeMap<string,GameObject> attrs;
+	private TreeMap<string,byte> attrs;
 	// string nodeId = new VMID().toString();
 
-	private static List<TreeNode> NIL_LIST = new List<TreeNode>();
+	private static readonly List<TreeNode> NIL_LIST = new List<TreeNode>();
 
 	public DefaultTreeNode() 
-		: this (NIL_LIST, new TreeMap<string,GameObject> ())
+		: this (NIL_LIST, new TreeMap<string,byte> ())
 	{
 	}
 
-	public DefaultTreeNode(List<TreeNode> _children, TreeMap<string, GameObject> _attrs) {
+	public DefaultTreeNode(List<TreeNode> _children, TreeMap<string, byte> _attrs) {
 		attrs = _attrs;
 		children = _children;
 	}
@@ -33,7 +33,7 @@
 	}
 
 	public Either<Error, TreeNode> appendRootNode() {
-		TreeNodeChildren newRootChildren = new DefaultTreeNodeChildren(NIL_LIST, new TreeMap<string,GameObject>());
+		TreeNodeChildren newRootChildren = new DefaultTreeNodeChildren(NIL_LIST, new TreeMap<string, byte>());
 		Either<Error, TreeNode> either = newRootChildren.addNewChildAt(0,this);
 		return either;
 	}