diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 6c3856d26f7..a26424372a0 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -1,5 +1,5 @@
@@ -301,20 +301,22 @@ PostgreSQL documentation
expression = NULL
because NULL> is not equal to
NULL>. (The null value represents an unknown value,
- and it is not known whether two unknown values are equal.)
+ and it is not known whether two unknown values are equal.) This
+ behavior conforms to the SQL standard.
- Some applications may (incorrectly) require that
+ Some applications may expect that
expression = NULL
returns true if expression evaluates to
- the null value. To support these applications, the run-time option
- transform_null_equals can be turned on (e.g.,
- SET transform_null_equals TO ON;).
- PostgreSQL will then convert
- x = NULL clauses to
- x IS NULL. This was
- the default behavior in releases 6.5 through 7.1.
+ the null value. It is highly recommended that these applications
+ be modified to comply with the SQL standard. However, if that
+ cannot be done the transform_null_equals
+ configuration variable is available. If it is enabled,
+ PostgreSQL will convert x =
+ NULL clauses to x IS NULL. This was
+ the default behavior in PostgreSQL
+ releases 6.5 through 7.1.