diff --git a/doc/src/sgml/catalogs.sgml b/doc/src/sgml/catalogs.sgml
index 43d7a1ad90..9536c57426 100644
--- a/doc/src/sgml/catalogs.sgml
+++ b/doc/src/sgml/catalogs.sgml
@@ -5945,6 +5945,7 @@ SCRAM-SHA-256$<replaceable>&lt;iteration count&gt;</replaceable>:<replaceable>&l
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
        <structfield>protrftypes</structfield> <type>oid[]</type>
+       (references <link linkend="catalog-pg-type"><structname>pg_type</structname></link>.<structfield>oid</structfield>)
       </para>
       <para>
        Data type OIDs for which to apply transforms.