Index: index.html
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--- index.html	(revision 9636)
+++ index.html	(revision 9637)
@@ -439,7 +439,7 @@
 	<tr><td> top/component copper layer<td> layer group with copper layers <td> any group of copper layers defined as the 'top' of a board
 	<tr><td> bottom/solder copper layer<td> layer group with copper layers <td>
 	any group of copper layers defined as the 'bottom' of a board
-	<tr><td> substrate                 <td> N/A<td> pcb-rnd does not currently handle phyiscal substrate information 
+	<tr><td> substrate                 <td> layer group makred as substrate, hosting no logical layers<td> pcb-rnd does not yet handle properties of phyiscal substrate information
 	<tr><td> contour of the board      <td> outline layer<td> designed using standard pcb-rnd elemnts
 	<tr><td> outline routing path      <td> outline layer<td> designed using standard pcb-rnd elemnts
 	<tr><td> polygon pour              <td> polygon<td> an object available for design in any layer group