Index: index.html
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--- index.html	(revision 18038)
+++ index.html	(revision 18039)
@@ -75,9 +75,10 @@
 layers in a layer group are toggled together. Having more than one layer
 in a group may be useful to:
 <ul>
-	<li> exploit that layers have different drawing color on screen: e.g. there
-	     can be a signal and a gnd layers with different color in the same
-	     layer group, on the same physical layer.
+	<li> exploit that layers have different
+	     <a href="../09_appendix/layer_colors.html">drawing color on screen:</a>
+	     e.g. there can be a signal and a gnd layers with different color in
+	     the same layer group, on the same physical layer.
 	<li> on composite-groups (mask, paste, silk), layers are combined using
 	     their properties: some layers may draw, others may clear; some layers
 	     may contain auto-generated objects. The order of layers does matter