diff --git a/reference/datetime/datetime.xml b/reference/datetime/datetime.xml
index e2fd667230..2d57a56058 100644
--- a/reference/datetime/datetime.xml
+++ b/reference/datetime/datetime.xml
@@ -89,6 +89,12 @@
      <varname linkend="datetime.constants.rfc3339">DateTime::RFC3339</varname>
      <initializer>"Y-m-d\TH:i:sP"</initializer>
     </fieldsynopsis>
+    <fieldsynopsis>
+     <modifier>const</modifier>
+     <type>string</type>
+     <varname linkend="datetime.constants.rfc3339_extended">DateTime::RFC3339_EXTENDED</varname>
+     <initializer>"Y-m-d\TH:i:s.vP"</initializer>
+    </fieldsynopsis>
     <fieldsynopsis>
      <modifier>const</modifier>
      <type>string</type>
@@ -224,6 +230,16 @@
      </listitem>
     </varlistentry>
 
+    <varlistentry xml:id="datetime.constants.rfc3339_extended">
+     <term><constant>DateTime::RFC3339_EXTENDED</constant></term>
+     <term><constant>DATE_RFC3339_EXTENDED</constant></term>
+     <listitem>
+      <simpara>
+       RFC 3339 EXTENDED format (since PHP 7.0.0) (example: 2005-08-15T15:52:01.000+00:00)
+      </simpara>
+     </listitem>
+    </varlistentry>
+
     <varlistentry xml:id="datetime.constants.rss">
      <term><constant>DateTime::RSS</constant></term>
      <term><constant>DATE_RSS</constant></term>
@@ -261,6 +277,13 @@
       </row>
      </thead>
      <tbody>
+      <row>
+       <entry>7.0.0</entry>
+       <entry>
+        Added constants: <link linkend="datetime.constants.rfc3339_extended">DATE_RFC3339_EXTENDED</link> and
+        <link linkend="datetime.constants.rfc3339_extended">DateTime::RFC3339_EXTENDED</link>.
+       </entry>
+      </row>
       <row>
        <entry>5.5.0</entry>
        <entry>