diff --git a/src/backend/optimizer/README b/src/backend/optimizer/README
index f341d9f303c..21c2db5a85c 100644
--- a/src/backend/optimizer/README
+++ b/src/backend/optimizer/README
@@ -143,7 +143,6 @@ For example:
     {1 2},{2 3},{3 4}
     {1 2 3},{2 3 4}
     {1 2 3 4}
-    (other possibilities will be excluded for lack of join clauses)
 
     SELECT  *
     FROM    tab1, tab2, tab3, tab4
@@ -156,6 +155,11 @@ For example:
     {1 2 3},{1 3 4},{1 2 4}
     {1 2 3 4}
 
+In each of these examples, other join-order possibilities will be excluded
+for lack of join clauses.  (In reality, use of EquivalenceClasses would
+allow us to deduce additional join clauses that allow more join orders,
+but here we ignore that to preserve the simplicity of the examples.)
+
 We consider left-handed plans (the outer rel of an upper join is a joinrel,
 but the inner is always a single list item); right-handed plans (outer rel
 is always a single item); and bushy plans (both inner and outer can be