Add metadata field references

Author: PatAltimore

articles/iot-operations/connect-to-cloud/howto-create-dataflow.md

@@ -592,9 +592,11 @@ To filter the data on a condition, you can use the `filter` stage. The condition
     | Filter condition   | The condition to filter the data based on a field in the source data.                               |
     | Description        | Provide a description for the filter condition.                                                     |
 
-    In the filter condition field, type `@` or select **Ctrl + Space** to select datapoints from a dropdown. You can also enter $metadata headers using the format `@$metadata.<header>`.
+    In the filter condition field, type `@` or select **Ctrl + Space** to select datapoints from a dropdown.
 
-    The condition can use the fields in the source data. For example, you could use a filter condition like `temperature > 20` to filter data less than or equal to 20 based on the temperature field.
+    You can access MQTT metadata properties using the format `@$metadata.user_properties.<property>` or `@$metadata.topic`. You can also enter $metadata headers using the format `@$metadata.<header>`. For more information, see [field references](concept-dataflow-mapping.md#field-references)
+
+    The condition can use the fields in the source data. For example, you could use a filter condition like `@temperature > 20` to filter data less than or equal to 20 based on the temperature field.
 
 1. Select **Apply**.
 
@@ -660,8 +662,10 @@ You can use the **Compute** transform to apply a formula to the source data. Thi
     | Last known value   | Optionally, use the last known value if the current value isn't available.                       |
 
 
-    You can enter or edit a formula in the **Formula** field. The formula can use the fields in the source data. Type `@` or select **Ctrl + Space** to select datapoints from a dropdown. You can also enter $metadata headers using the format `@$metadata.<header>`.
-    
+    You can enter or edit a formula in the **Formula** field. The formula can use the fields in the source data. Type `@` or select **Ctrl + Space** to select datapoints from a dropdown.
+
+    You can access MQTT metadata properties using the format `@$metadata.user_properties.<property>` or `@$metadata.topic`. You can also enter $metadata headers using the format `@$metadata.<header>`. For more information, see [field references](concept-dataflow-mapping.md#field-references).
+
     The formula can use the fields in the source data. For example, you could use the `temperature` field in the source data to convert the temperature to Celsius and store it in the `temperatureCelsius` output field. 
 
 1. Select **Apply**.
@@ -682,6 +686,8 @@ You can rename a datapoint using the **Rename** transform. This operation is use
     | New datapoint name | Enter the new name for the datapoint.                                                                   |
     | Description        | Provide a description for the transformation.                                                           |
 
+    You can access MQTT metadata properties using the format `@$metadata.user_properties.<property>` or `@$metadata.topic`. You can also enter $metadata headers using the format `@$metadata.<header>`. For more information, see [field references](concept-dataflow-mapping.md#field-references).
+
 1. Select **Apply**.
 
 #### New property