Index: trunk/src/layer.h
===================================================================
--- trunk/src/layer.h	(revision 34555)
+++ trunk/src/layer.h	(revision 34556)
@@ -162,9 +162,10 @@
 rnd_layer_id_t pcb_layer_id(const pcb_data_t *Data, const pcb_layer_t *Layer);
 
 
-/* the offsets of the two additional special layers (e.g. silk) for 'component'
-   and 'solder'. The offset of PCB_MAX_LAYER is not added here. Also can be
-   used to address side of the board without referencing to groups or layers. */
+/* Sddress side of the board without referencing to groups or layers.
+   (Historical use: in io_pcb the index offsets of the two additional
+   special layers (e.g. silk) for 'component' and 'solder'.
+   The offset of PCB_MAX_LAYER is not added here.) */
 typedef enum {
 	PCB_SOLDER_SIDE    = 0,
 	PCB_COMPONENT_SIDE = 1