diff --git a/mpl/bup1.py b/mpl/bup1.py
index 5635eab..dc62445 100644
--- a/mpl/bup1.py
+++ b/mpl/bup1.py
@@ -1,8 +1,12 @@
-# Copyright (c) 2008 Andreas Balogh
+# Copyright (c) 2009 Andreas Balogh
 # See LICENSE for details.
 
 '''
-online bottom up 
+Online bottom-up
+
+1. segment tick data with a sliding window alogrithm
+2. recognise low/high points by comparing slope information
+3. recognise trend by observing low/high point difference 
 '''
 
 # system imports
@@ -250,7 +254,7 @@ class DelayedAcp:
 
 
 class TopDownLoHi:
-    '''Time series high & low detector.'''
+    '''Douglas-Peucker algorithm.'''
     def __init__(self, bias):
         assert(bias > 0) 
         self.bias = bias