diff --git a/docs_src/microservices/core/metadata/details/DeviceSystemEvents.md b/docs_src/microservices/core/metadata/details/DeviceSystemEvents.md
index ee4326dc18..884d574fb8 100644
--- a/docs_src/microservices/core/metadata/details/DeviceSystemEvents.md
+++ b/docs_src/microservices/core/metadata/details/DeviceSystemEvents.md
@@ -21,7 +21,7 @@ The System Event DTO has the following properties:
 | Owner     | Owner of the data in the System Event         | In this case it is the name of the device service that owns the device or `core-metadata` |
 | Tags      | Key value map of additional data              | empty in this case                                           |
 | Details   | The data object that trigger the System Event | the added, updated, or deleted Device/Device Profile/Device Service/Provision Watcher in this case           |
-| Timestamp | Date and time of the System Event             | timestamp                                                    |
+| Timestamp | Date and time of the System Event             | timestamp in nanoseconds                                     |
 
 ## Publish Topic
 
diff --git a/docs_src/microservices/general/index.md b/docs_src/microservices/general/index.md
index 8d36b4fd8a..ef4b58d76c 100644
--- a/docs_src/microservices/general/index.md
+++ b/docs_src/microservices/general/index.md
@@ -131,4 +131,26 @@ Only `httpheader` is currently supported. The `headername` specifies the authent
     ```
     GET https://example.com/uom.yaml HTTP/1.1
     <name>: <contents>
-    ```
\ No newline at end of file
+    ```
+
+
+### Timestamp Precision
+
+We have several data models with a timestamp field, but the precision varies, please refer to the following measurements and examples:
+
+- `created` and `modified` field cross different data models are in <b>milliseconds</b>, see [Core Metadata API documentation][1] for more information.
+
+    For example, the `created` and `modified` fields in the device object of the Core Metadata Service.
+
+- `start` and `end` timestamp in the Cron Scheduler Service are in <b>milliseconds</b>, see [Cron Scheduler Service API documentation][2] for more information.
+
+- `timestamp` in Metrics and System Events are in <b>nanoseconds</b>, see [Service Metrics][3] and [System Events DTO][4] for more information.
+
+- `origin` in Event and Readings is in <b>nanoseconds</b>, see [Origin Timestamp][5] for more information.
+
+
+[1]: ../core/metadata/ApiReference.md
+[2]: ../support/cronScheduler/ApiReference.md
+[3]: #service-metrics
+[4]: ../core/metadata/details/DeviceSystemEvents.md#system-event-dto
+[5]: ../../walk-through/Ch-WalkthroughReading.md#origin-timestamp
\ No newline at end of file