diff --git a/ChangeLog b/ChangeLog
index 9e3670093c..88566a807a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Mon Oct  6 11:21:21 2014  Martin Duerst <duerst@it.aoyama.ac.jp>
+
+	* tool/unicode_norm_gen.rb: Adding/tweaking comments.
+
 Mon Oct  6 10:57:57 2014  Martin Duerst <duerst@it.aoyama.ac.jp>
 
 	* tool/unicode_norm_gen.rb: Adjusted directory paths.
diff --git a/tool/unicode_norm_gen.rb b/tool/unicode_norm_gen.rb
index 03a32bbdc5..c90b16dac5 100644
--- a/tool/unicode_norm_gen.rb
+++ b/tool/unicode_norm_gen.rb
@@ -1,14 +1,17 @@
 # coding: utf-8
 
-# Copyright 2010-2013 Ayumu Nojima (野島 歩) and Martin J. Dürst (duerst@it.aoyama.ac.jp)
-# available under the same licence as Ruby itself
-# (see http://www.ruby-lang.org/en/LICENSE.txt)
+# Copyright Ayumu Nojima (野島 歩) and Martin J. Dürst (duerst@it.aoyama.ac.jp)
 
+# Script to generate Ruby data structures used in implementing
+# String#unicode_normalize,...
+
+# Constants for input and ouput directory
 InputDataDir = '../enc/unicode/data'
 OuputDataDir = '../lib/unicode_normalize'
 
+# convenience methods
 class Integer
-  def to_UTF8()
+  def to_UTF8() # convert to string, taking legibility into account
     if self>0xFFFF
       "\\u{#{to_s(16).upcase}}"
     elsif CombiningClass[self] or self=='\\'.ord or self=='"'.ord
@@ -135,7 +138,7 @@ end.line_slice "\n    "
 open("#{OuputDataDir}/normalize_tables.rb", "w").print <<MAPPING_TABLE_FILE_END
 # coding: utf-8
 
-# automatically generated by generate.rb
+# automatically generated by tool/unicode_norm_gen.rb
 
 module Normalize
   ACCENTS = "