diff --git a/base_classes/NXentry.nxdl.xml b/base_classes/NXentry.nxdl.xml
index 6641a1ad04..368845f032 100644
--- a/base_classes/NXentry.nxdl.xml
+++ b/base_classes/NXentry.nxdl.xml
@@ -124,6 +124,36 @@
 		<doc>UUID identifier for the measurement.</doc>
 		<attribute name="version"><doc>Version of UUID used</doc></attribute>
 	</field>
+	<field name="experiment_location">
+        <doc>City and country where the experiment took place</doc>
+    </field>
+    <field name="experiment_start_date" type="NX_DATE_TIME">
+        <doc>
+            Start time of experimental run that includes the current
+            measurement, for example a beam time.
+        </doc>
+    </field>
+    <field name="experiment_end_date" type="NX_DATE_TIME">
+        <doc>
+             End time of experimental run that includes the current
+             measurement, for example a beam time.
+        </doc>
+    </field>
+    <field name="experiment_institution">
+        <doc>
+             Name of the institution hosting the facility
+        </doc>
+    </field>
+    <field name="experiment_facility">
+        <doc>
+             Name of the experimental facility
+        </doc>
+    </field>
+    <field name="experiment_laboratory">
+        <doc>
+             Name of the laboratory or beamline
+        </doc>
+    </field>
 	<field name="features">
 		<doc>
 			Reserved for future use by NIAC.
diff --git a/base_classes/NXsubentry.nxdl.xml b/base_classes/NXsubentry.nxdl.xml
index 377369b106..ae5478a2b9 100644
--- a/base_classes/NXsubentry.nxdl.xml
+++ b/base_classes/NXsubentry.nxdl.xml
@@ -104,6 +104,36 @@
 	<field name="entry_identifier">
 		<doc>unique identifier for the measurement, defined by the facility.</doc>
 	</field>
+	<field name="experiment_location">
+        <doc>City and country where the experiment took place</doc>
+    </field>
+    <field name="experiment_start_date" type="NX_DATE_TIME">
+        <doc>
+            Start time of experimental run that includes the current
+            measurement, for example a beam time.
+        </doc>
+    </field>
+    <field name="experiment_end_date" type="NX_DATE_TIME">
+        <doc>
+             End time of experimental run that includes the current
+             measurement, for example a beam time.
+        </doc>
+    </field>
+    <field name="experiment_institution">
+        <doc>
+             Name of the institution hosting the facility
+        </doc>
+    </field>
+    <field name="experiment_facility">
+        <doc>
+             Name of the experimental facility
+        </doc>
+    </field>
+    <field name="experiment_laboratory">
+        <doc>
+             Name of the laboratory or beamline
+        </doc>
+    </field>
 	<field name="definition">
 		<doc>Official NeXus NXDL schema to which this subentry conforms</doc>
 		<attribute name="version"><doc>NXDL version number</doc></attribute>