diff --git a/doc/src/sgml/plpgsql.sgml b/doc/src/sgml/plpgsql.sgml
index 7f23c2f..5d4080f 100644
--- a/doc/src/sgml/plpgsql.sgml
+++ b/doc/src/sgml/plpgsql.sgml
@@ -3660,18 +3660,26 @@ ASSERT condition , in PL/pgSQL
+
+ PL/pgSQL can be used to define trigger
+ procedures on data changes or database events.
+ A trigger procedure is created with the CREATE FUNCTION> command,
+ declaring it as a function with no arguments and a return type of
+ trigger> (for data change triggers) or
+ event_trigger> (for database event triggers).
+ Special variables PG_something>> are automatically
+ available to test the condition which triggered the call.
+
+
Triggers on Data Changes
-
- PL/pgSQL can be used to define trigger
- procedures. A trigger procedure is created with the
- CREATE FUNCTION> command, declaring it as a function with
- no arguments and a return type of trigger. Note that
- the function must be declared with no arguments even if it expects
- to receive arguments specified in CREATE TRIGGER> —
- trigger arguments are passed via TG_ARGV>, as described
- below.
+
+ A data change trigger> is declared as a function
+ with no arguments and a return type of trigger>.
+ Note that the function must be declared with no arguments even if it expects
+ to receive arguments specified in CREATE TRIGGER> —
+ trigger arguments are passed via TG_ARGV>, as described below.
@@ -4218,8 +4226,9 @@ SELECT * FROM sales_summary_bytime;
Triggers on Events
- PL/pgSQL can be used to define event
- triggers. PostgreSQL> requires that a procedure that
+ PL/pgSQL can be used to define
+ event triggers>.
+ PostgreSQL> requires that a procedure that
is to be called as an event trigger must be declared as a function with
no arguments and a return type of event_trigger>.