diff --git a/src/com/bytezone/diskbrowser/disk/AppleDisk.java b/src/com/bytezone/diskbrowser/disk/AppleDisk.java
index d162b85..6a466c5 100755
--- a/src/com/bytezone/diskbrowser/disk/AppleDisk.java
+++ b/src/com/bytezone/diskbrowser/disk/AppleDisk.java
@@ -45,6 +45,20 @@ public class AppleDisk implements Disk
   // Position: 0 8 1 9 2 A 3 B 4 C 5 D 6 E 7 F    - Prodos (.PO disks)
   // Position: 0 7 E 6 D 5 C 4 B 3 A 2 9 1 8 F    - Dos    (.DO disks)
 
+  // https://github.com/AppleWin/AppleWin/blob/master/source/DiskImageHelper.cpp
+  // DO logical order  0 1 2 3 4 5 6 7 8 9 A B C D E F */
+  //    physical order 0 D B 9 7 5 3 1 E C A 8 6 4 2 F */
+
+  // PO logical order  0 E D C B A 9 8 7 6 5 4 3 2 1 F */
+  //    physical order 0 2 4 6 8 A C E 1 3 5 7 9 B D F */
+
+  //BYTE CImageBase::ms_SectorNumber[NUM_SECTOR_ORDERS][0x10] =
+  //{
+  //  {0x00,0x08,0x01,0x09,0x02,0x0A,0x03,0x0B, 0x04,0x0C,0x05,0x0D,0x06,0x0E,0x07,0x0F},
+  //  {0x00,0x07,0x0E,0x06,0x0D,0x05,0x0C,0x04, 0x0B,0x03,0x0A,0x02,0x09,0x01,0x08,0x0F},
+  //  {0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00}
+  //}; 
+
   private boolean[] hasData;
   private byte emptyByte = 0;