diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index cffca4e46c9f38e03ad74b81160d9cb5f4f7d5da..4728ca5cf46ba66961368b1ceedad25ba188d5df 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -1662,6 +1662,9 @@ SET ENABLE_SEQSCAN TO OFF;
         to allow the transaction to commit asynchronously.  However, the
         special value <literal>local</> is available for transactions that
         wish to wait for local flush to disk, but not synchronous replication.
+        If <varname>synchronous_standby_names</> is not set, <literal>on</>,
+        <literal>remote_write</> and <literal>local</> provide the same
+        synchronization level; transaction commit only waits for local flush.
        </para>
        <para>
         This parameter can be changed at any time; the behavior for any