Index: index.html
===================================================================
--- index.html	(revision 19276)
+++ index.html	(revision 19277)
@@ -90,7 +90,7 @@
 layers in them. The mask, paste, silk layer groups behave the same and
 can host zero or more logical layers.
 <p>
-Each layer group has a type. Types are:
+Each layer group has a main type. Main types are:
 <ul>
 	<li> <b>copper</b>   for signal layers
 	<li> <b>silk</b>     for silkscreen layers