--- a/services/healthreport/docs/dataformat.rst
+++ b/services/healthreport/docs/dataformat.rst
@@ -240,16 +240,20 @@ Leading by example::
                 ],
                 "_v": "4"
               },
               "org.mozilla.searches.counts": {
                 "bartext": {
                   "google": 1
                 },
                 "_v": "4"
+              },
+              "org.mozilla.experiment": {
+                "lastActive": "some.experiment.id"
+                "_v": "1"
               }
             }
           }
         }
       }
     }
 
 App sessions in Version 3
@@ -1456,8 +1460,34 @@ Example
       "_v": 1,
       "cpuCount": 8,
       "memoryMB": 8192,
       "architecture": "x86-64",
       "name": "Darwin",
       "version": "12.2.0"
     }
 
+
+
+org.mozilla.experiments.info
+----------------------------------
+
+Daily measurement reporting information about the Telemetry Experiments service.
+
+Version 1
+^^^^^^^^^
+
+Property:
+
+lastActive
+    ID of the final Telemetry Experiment that is active on a given day, if any.
+
+
+Example
+^^^^^^^
+
+::
+
+    "org.mozilla.experiments.info": {
+      "_v": 1,
+      "lastActive": "some.experiment.id"
+    }
+