Index: 09_appendix/action_src/undo.html
===================================================================
--- 09_appendix/action_src/undo.html	(revision 34203)
+++ 09_appendix/action_src/undo.html	(revision 34204)
@@ -13,6 +13,8 @@
 <ul>
 	<li> FreezeSerial: stop increasing the undo serial number
 	<li> UnFreezeSerial: stop increasing the undo serial number
+	<li> FreezeAdd: stop adding operations to the undo list
+	<li> UnFreezeAdd: start adding operations to the undo list again
 	<li> IncSerial: increase the undo serial number (operations with the same serial number are batched); a typical sequence for batching operations is: Undo(FreezeSerial); ...; Undo(UnFreezeSerial); Undo(IcSerial)
 	<li> GetSerial: return the current undo serial
 	<li> GetNum: return the number of undo slots currently allocated