diff --git a/doc/sql.extensions/README.order_by_expressions_nulls b/doc/sql.extensions/README.order_by_expressions_nulls
index 1f1d6c0e39..01997e6968 100644
--- a/doc/sql.extensions/README.order_by_expressions_nulls
+++ b/doc/sql.extensions/README.order_by_expressions_nulls
@@ -18,7 +18,7 @@ nulls_placement : NULLS FIRST | NULLS LAST;
    it is interpreted as column number. The nulls_placement clause
    controls ordering of nulls in result set. They can be sorted
    either above (NULLS FIRST) or below (NULLS LAST) of all other values.
-   Behaviour when nulls_placement is unspecified is NULLS LAST.   
+   Behaviour when nulls_placement is unspecified is NULLS FIRST.   
 
 Author:
    Nickolay Samofatov <skidder@bssys.com>
@@ -27,8 +27,10 @@ Author:
 N O T E S
 =========
 
- - Index is never used for ordering if you specify NULLS FIRST
-   as a nulls_placement
+ - If you override the default nulls placement, no index can be used
+   for sorting. That is, no index will be used for an ASCENDING sort
+   if NULLS LAST is specified, nor for a DESCENDING sort
+   if NULLS FIRST is specified.
  - Results are undefined if you ask engine to sort results using 
    non-deterministic UDF or stored procedure.
  - Amount of procedure invocations is undefined if you ask engine to