diff --git a/doc/src/sgml/event-trigger.sgml b/doc/src/sgml/event-trigger.sgml
index 36928413d15..7343227d28f 100644
--- a/doc/src/sgml/event-trigger.sgml
+++ b/doc/src/sgml/event-trigger.sgml
@@ -106,7 +106,7 @@
 
    <table id="event-trigger-by-command-tag">
      <title>Event Trigger Support by Command Tag</title>
-     <tgroup cols="3">
+     <tgroup cols="4">
       <thead>
        <row>
         <entry>command tag</entry>