diff --git a/reference/datetime/datetime/add.xml b/reference/datetime/datetime/add.xml
index bd6c779af8..73ca8c1d75 100644
--- a/reference/datetime/datetime/add.xml
+++ b/reference/datetime/datetime/add.xml
@@ -20,7 +20,7 @@
   <para>&style.procedural;</para>
   <methodsynopsis>
    <type>DateTime</type><methodname>date_add</methodname>
-   <methodparam><type>DateTime</type><parameter>object</parameter></methodparam>
+   <methodparam><type>DateTime</type><parameter role="reference">object</parameter></methodparam>
    <methodparam><type>DateInterval</type><parameter>interval</parameter></methodparam>
   </methodsynopsis>
   <para>
diff --git a/reference/datetime/datetime/modify.xml b/reference/datetime/datetime/modify.xml
index 63a40f4c08..edfbe89595 100644
--- a/reference/datetime/datetime/modify.xml
+++ b/reference/datetime/datetime/modify.xml
@@ -17,7 +17,7 @@
   <para>&style.procedural;</para>
   <methodsynopsis>
    <type>DateTime</type><methodname>date_modify</methodname>
-   <methodparam><type>DateTime</type><parameter>object</parameter></methodparam>
+   <methodparam><type>DateTime</type><parameter role="reference">object</parameter></methodparam>
    <methodparam><type>string</type><parameter>modify</parameter></methodparam>
   </methodsynopsis>
   <para>
diff --git a/reference/datetime/datetime/setdate.xml b/reference/datetime/datetime/setdate.xml
index cea86c2766..5fc478d778 100644
--- a/reference/datetime/datetime/setdate.xml
+++ b/reference/datetime/datetime/setdate.xml
@@ -19,7 +19,7 @@
   <para>&style.procedural;</para>
   <methodsynopsis>
    <type>DateTime</type><methodname>date_date_set</methodname>
-   <methodparam><type>DateTime</type><parameter>object</parameter></methodparam>
+   <methodparam><type>DateTime</type><parameter role="reference">object</parameter></methodparam>
    <methodparam><type>int</type><parameter>year</parameter></methodparam>
    <methodparam><type>int</type><parameter>month</parameter></methodparam>
    <methodparam><type>int</type><parameter>day</parameter></methodparam>
diff --git a/reference/datetime/datetime/setisodate.xml b/reference/datetime/datetime/setisodate.xml
index b53695c93f..15611ae735 100644
--- a/reference/datetime/datetime/setisodate.xml
+++ b/reference/datetime/datetime/setisodate.xml
@@ -19,7 +19,7 @@
   <para>&style.procedural;</para>
   <methodsynopsis>
    <type>DateTime</type><methodname>date_isodate_set</methodname>
-   <methodparam><type>DateTime</type><parameter>object</parameter></methodparam>
+   <methodparam><type>DateTime</type><parameter role="reference">object</parameter></methodparam>
    <methodparam><type>int</type><parameter>year</parameter></methodparam>
    <methodparam><type>int</type><parameter>week</parameter></methodparam>
    <methodparam choice="opt"><type>int</type><parameter>day</parameter><initializer>1</initializer></methodparam>
diff --git a/reference/datetime/datetime/settime.xml b/reference/datetime/datetime/settime.xml
index 05a3239d58..8c4c1b29f7 100644
--- a/reference/datetime/datetime/settime.xml
+++ b/reference/datetime/datetime/settime.xml
@@ -19,7 +19,7 @@
   <para>&style.procedural;</para>
   <methodsynopsis>
    <type>DateTime</type><methodname>date_time_set</methodname>
-   <methodparam><type>DateTime</type><parameter>object</parameter></methodparam>
+   <methodparam><type>DateTime</type><parameter role="reference">object</parameter></methodparam>
    <methodparam><type>int</type><parameter>hour</parameter></methodparam>
    <methodparam><type>int</type><parameter>minute</parameter></methodparam>
    <methodparam choice="opt"><type>int</type><parameter>second</parameter><initializer>0</initializer></methodparam>
diff --git a/reference/datetime/datetime/settimestamp.xml b/reference/datetime/datetime/settimestamp.xml
index c7b6a4a85c..55de445280 100644
--- a/reference/datetime/datetime/settimestamp.xml
+++ b/reference/datetime/datetime/settimestamp.xml
@@ -17,7 +17,7 @@
   <para>&style.procedural;</para>
   <methodsynopsis>
    <type>DateTime</type><methodname>date_timestamp_set</methodname>
-   <methodparam><type>DateTime</type><parameter>object</parameter></methodparam>
+   <methodparam><type>DateTime</type><parameter role="reference">object</parameter></methodparam>
    <methodparam><type>int</type><parameter>unixtimestamp</parameter></methodparam>
   </methodsynopsis>
   <para>
diff --git a/reference/datetime/datetime/settimezone.xml b/reference/datetime/datetime/settimezone.xml
index f40fdf49b2..85f0275695 100644
--- a/reference/datetime/datetime/settimezone.xml
+++ b/reference/datetime/datetime/settimezone.xml
@@ -17,7 +17,7 @@
   <para>&style.procedural;</para>
   <methodsynopsis>
    <type>DateTime</type><methodname>date_timezone_set</methodname>
-   <methodparam><type>DateTime</type><parameter>object</parameter></methodparam>
+   <methodparam><type>DateTime</type><parameter role="reference">object</parameter></methodparam>
    <methodparam><type>DateTimeZone</type><parameter>timezone</parameter></methodparam>
   </methodsynopsis>
  </refsect1>
diff --git a/reference/datetime/datetime/sub.xml b/reference/datetime/datetime/sub.xml
index 370a0da72a..b1cd4b078e 100644
--- a/reference/datetime/datetime/sub.xml
+++ b/reference/datetime/datetime/sub.xml
@@ -20,7 +20,7 @@
   <para>&style.procedural;</para>
   <methodsynopsis>
    <type>DateTime</type><methodname>date_sub</methodname>
-   <methodparam><type>DateTime</type><parameter>object</parameter></methodparam>
+   <methodparam><type>DateTime</type><parameter role="reference">object</parameter></methodparam>
    <methodparam><type>DateInterval</type><parameter>interval</parameter></methodparam>
   </methodsynopsis>
   <para>