diff --git a/change_log.txt b/change_log.txt
index 3819568461..a854c44ecd 100644
--- a/change_log.txt
+++ b/change_log.txt
@@ -9,7 +9,7 @@ email address.
 ================================================================================
 + pcbnew
     Added dedicated Show() function for SEGVIA.  Enhanced BOARD_ITEM::MenuText()
-    for SEGVIA.  Added to todo.txt.
+    for SEGVIA.
 
 
 2007-Sep-29 UPDATE   Dick Hollenbeck <dick@softplc.com>
diff --git a/include/pcbstruct.h b/include/pcbstruct.h
index fb597c9e13..0267a4c477 100644
--- a/include/pcbstruct.h
+++ b/include/pcbstruct.h
@@ -34,46 +34,6 @@
 #define CHAIN       0x01    /* segment marque  */
 
 
-/*************************************/
-/* constantes de gestion des couches */
-/*************************************/
-#define CUIVRE_LAYER            0x00000001      /* Bit layer cuivre */
-#define LAYER_2                 0x00000002      /* Bit layer 2 */
-#define LAYER_3                 0x00000004      /* Bit layer 3 */
-#define LAYER_4                 0x00000008      /* Bit layer 4 */
-#define LAYER_5                 0x00000010      /* Bit layer 5 */
-#define LAYER_6                 0x00000020      /* Bit layer 6 */
-#define LAYER_7                 0x00000040      /* Bit layer 7 */
-#define LAYER_8                 0x00000080      /* Bit layer 8 */
-#define LAYER_9                 0x00000100      /* Bit layer 9 */
-#define LAYER_10                0x00000200      /* Bit layer 10 */
-#define LAYER_11                0x00000400      /* Bit layer 11 */
-#define LAYER_12                0x00000800      /* Bit layer 12 */
-#define LAYER_13                0x00001000      /* Bit layer 13 */
-#define LAYER_14                0x00002000      /* Bit layer 14 */
-#define LAYER_15                0x00004000      /* Bit layer 15 */
-#define CMP_LAYER               0x00008000      /* Bit layer cmp */
-#define ADHESIVE_LAYER_CU       0x00010000
-#define ADHESIVE_LAYER_CMP      0x00020000
-#define SOLDERPASTE_LAYER_CU    0x00040000
-#define SOLDERPASTE_LAYER_CMP   0x00080000
-#define SILKSCREEN_LAYER_CU     0x00100000
-#define SILKSCREEN_LAYER_CMP    0x00200000
-#define SOLDERMASK_LAYER_CU     0x00400000
-#define SOLDERMASK_LAYER_CMP    0x00800000
-#define DRAW_LAYER              0x01000000
-#define COMMENT_LAYER           0x02000000
-#define ECO1_LAYER              0x04000000
-#define ECO2_LAYER              0x08000000
-#define EDGE_LAYER              0x10000000
-//      extra bits              0xE0000000
-/* masques generaux : */
-#define ALL_LAYERS              0x1FFFFFFF
-#define ALL_NO_CU_LAYERS        0x1FFF0000
-#define ALL_CU_LAYERS           0x0000FFFF
-#define INTERNAL_LAYERS         0x00007FFE      /* Bits layers internes */
-#define EXTERNAL_LAYERS         0x00008001
-
 /* Flags pour les couches cuivres */
 /* numero des couches particulieres */
 #define LAYER_CUIVRE_N        0
@@ -115,6 +75,47 @@
 
 #define LAYER_COUNT           32
 
+
+/*************************************/
+/* constantes de gestion des couches */
+/*************************************/
+#define CUIVRE_LAYER            (1<<LAYER_CUIVRE_N)     ///< bit mask for copper layer 
+#define LAYER_2                 (1<<LAYER_N_2)          ///< bit mask for layer 2
+#define LAYER_3                 (1<<LAYER_N_3)          ///< bit mask for layer 3
+#define LAYER_4                 (1<<LAYER_N_4)          ///< bit mask for layer 4
+#define LAYER_5                 (1<<LAYER_N_5)          ///< bit mask for layer 5
+#define LAYER_6                 (1<<LAYER_N_6)          ///< bit mask for layer 6
+#define LAYER_7                 (1<<LAYER_N_7)          ///< bit mask for layer 7
+#define LAYER_8                 (1<<LAYER_N_8)          ///< bit mask for layer 8
+#define LAYER_9                 (1<<LAYER_N_9)          ///< bit mask for layer 9
+#define LAYER_10                (1<<LAYER_N_10)         ///< bit mask for layer 10
+#define LAYER_11                (1<<LAYER_N_11)         ///< bit mask for layer 11
+#define LAYER_12                (1<<LAYER_N_12)         ///< bit mask for layer 12
+#define LAYER_13                (1<<LAYER_N_13)         ///< bit mask for layer 13
+#define LAYER_14                (1<<LAYER_N_14)         ///< bit mask for layer 14
+#define LAYER_15                (1<<LAYER_N_15)         ///< bit mask for layer 15
+#define CMP_LAYER               (1<<LAYER_CMP_N)        ///< bit mask for component layer
+#define ADHESIVE_LAYER_CU       (1<<ADHESIVE_N_CU)
+#define ADHESIVE_LAYER_CMP      (1<<ADHESIVE_N_CMP)
+#define SOLDERPASTE_LAYER_CU    (1<<SOLDERPASTE_N_CU)
+#define SOLDERPASTE_LAYER_CMP   (1<<SOLDERPASTE_N_CMP)
+#define SILKSCREEN_LAYER_CU     (1<<SILKSCREEN_N_CU)
+#define SILKSCREEN_LAYER_CMP    (1<<SILKSCREEN_N_CMP)
+#define SOLDERMASK_LAYER_CU     (1<<SOLDERMASK_N_CU)
+#define SOLDERMASK_LAYER_CMP    (1<<SOLDERMASK_N_CMP)
+#define DRAW_LAYER              (1<<DRAW_N)
+#define COMMENT_LAYER           (1<<COMMENT_N)
+#define ECO1_LAYER              (1<<ECO1_N)
+#define ECO2_LAYER              (1<<ECO2_N)
+#define EDGE_LAYER              (1<<EDGE_N)
+//      extra bits              0xE0000000
+/* masques generaux : */
+#define ALL_LAYERS              0x1FFFFFFF
+#define ALL_NO_CU_LAYERS        0x1FFF0000
+#define ALL_CU_LAYERS           0x0000FFFF
+#define INTERNAL_LAYERS         0x00007FFE      /* Bits layers internes */
+#define EXTERNAL_LAYERS         0x00008001
+
 /* Forme des segments (pistes, contours ..) ( parametre .shape ) */
 enum Track_Shapes {
     S_SEGMENT = 0,      /* segment rectiligne */
diff --git a/pcbnew/class_track.cpp b/pcbnew/class_track.cpp
index 630db23727..6733fc7f34 100644
--- a/pcbnew/class_track.cpp
+++ b/pcbnew/class_track.cpp
@@ -214,15 +214,19 @@ int TRACK::ReturnMaskLayer()
 {
     if( Type() == TYPEVIA )
     {
-        int via_type = m_Shape & 15;
+        int via_type = Shape();
+        
         if( via_type == VIA_NORMALE )
             return ALL_CU_LAYERS;
 
         // VIA_BORGNE ou  VIA_ENTERREE:
-        int bottom_layer = (m_Layer >> 4) & 15;
-        int top_layer    = m_Layer & 15;
-        if( bottom_layer > top_layer )
-            EXCHG( bottom_layer, top_layer );
+        
+        int bottom_layer;
+        int top_layer;
+
+        // ReturnLayerPair() knows how layers are stored
+        ((SEGVIA*)this)->ReturnLayerPair( &top_layer, &bottom_layer );
+        
         int layermask = 0;
         while( bottom_layer <= top_layer )
         {
@@ -272,8 +276,10 @@ void SEGVIA::ReturnLayerPair( int* top_layer, int* bottom_layer ) const
 
     if( b_layer > t_layer )
         EXCHG( b_layer, t_layer );
+    
     if( top_layer )
         *top_layer = t_layer;
+    
     if( bottom_layer )
         *bottom_layer = b_layer;
 }
diff --git a/pcbnew/class_track.h b/pcbnew/class_track.h
index 283f1b3de8..f09375de9d 100644
--- a/pcbnew/class_track.h
+++ b/pcbnew/class_track.h
@@ -96,8 +96,16 @@ public:
     /* divers */
     int Shape() const { return m_Shape & 0xFF; }
 
+    /**
+     * Function ReturnMaskLayer
+     * returns a "layer mask", which is a bitmap of all layers on which the 
+     * TRACK segment or SEGVIA physically resides.
+     * @return int - a layer mask, see pcbstruct.h's CUIVRE_LAYER, etc.
+     */
     int     ReturnMaskLayer();
+    
     int     IsPointOnEnds( const wxPoint& point, int min_dist = 0 );
+    
     bool    IsNull(); // return TRUE if segment lenght = 0
 
     
diff --git a/todo.txt b/todo.txt
index c841941e3a..7107c309c1 100644
--- a/todo.txt
+++ b/todo.txt
@@ -51,5 +51,3 @@ understanding by new developers.
 *** Implement the graying in/out of "Edit/Undo", "Edit/Redo" menu items, 
 when Undo/Redo stack is empty/filled.
 
-*** There is no way to truly edit a via, such as changing its layers.
-