diff --git a/doc_source/using-x-ray.md b/doc_source/using-x-ray.md
index edf1252c..87bb6ac0 100644
--- a/doc_source/using-x-ray.md
+++ b/doc_source/using-x-ray.md
@@ -32,8 +32,10 @@ From the service map, you can zoom in to see a trace view of your Lambda functio
   + **Attempt** – Represents a single invocation attempt, including any overhead introduced by the Lambda service\. Examples of overhead are time spent initializing the function's code and function execution time\.
 + **Lambda function segment** – Represents execution time for the function for a given invocation attempt\. It starts when the function handler starts executing and ends when the function terminates\. This segment can include three types of subsegments:
   + **Initialization** – The time spent running the `initialization` code of the function, defined as the code outside the Lambda function handler or static initializers\.
-  + **Downstream calls** – Calls made to other AWS services from the Lambda function's code\.
-  + **Custom subsegments** – Custom subsegments or user annotations that you can add to the Lambda function segment by using the X\-Ray SDK\. 
+  + **Downstream calls** – Calls made to other AWS services or downstream HTTP requests from the Lambda function's code\.
+  + **Custom subsegments** – Custom subsegments that you can add to the Lambda function segment by using the X\-Ray SDK\. 
+  
+The Lambda function segment is generated by the Lambda service on behalf of the customer. It overwrites any segment created in the Lambda function code, including segments generated by the X-Ray SDK to capture requests via middleware. If a segment is created in Lambda function code, it is implemented as a facade segment. The facade segment only allows custom subsegments to be added to and deleted from it; all other segment operations are treated as no-ops.
 
 **Note**  
-For each traced invocation, Lambda emits the Lambda service segment and all of its subsegments\. These segments are emitted regardless of the runtime and require you to use the X\-Ray SDK for AWS API calls\. 
\ No newline at end of file
+For each traced invocation, Lambda emits the Lambda service segment and all of its subsegments\. This segment and its subsegments are emitted regardless of the runtime you use\.