From 626a4ae698599c7b860d346816ef87f1ae22acf1 Mon Sep 17 00:00:00 2001
From: Quentin Ligier <quentin.ligier@bluewin.ch>
Date: Mon, 27 Jan 2025 10:54:33 +0100
Subject: [PATCH] Clarify the use of ActiveParticipants source and destination

---
 files/Atna.md | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/files/Atna.md b/files/Atna.md
index 4b276a6..ca319ae 100644
--- a/files/Atna.md
+++ b/files/Atna.md
@@ -51,7 +51,8 @@ Then, two _ActiveParticipants_ describe the source and destination participants.
 
 === "_ActiveParticipant_ source"
 
-    The first _ActiveParticipant_ describes the source participant, which is the one that has sent the transaction.
+    The first _ActiveParticipant_ describes the source participant, which often is the one that has sent the 
+    transaction (but not always).
     It has the following content:
     ```xml
     <ActiveParticipant UserID="★user_id" AlternativeUserID="★alt_user_id" NetworkAccessPointID="★nap_id" NetworkAccessPointTypeCode="★nap_type" UserIsRequest="true">
@@ -69,8 +70,8 @@ Then, two _ActiveParticipants_ describe the source and destination participants.
 
 === "_ActiveParticipant_ destination"
 
-    The second _ActiveParticipant_ describes the destination participant, which is the one that has received the 
-    transaction.
+    The second _ActiveParticipant_ describes the destination participant, which often is the one that has received the 
+    transaction (but not always).
     It has the following content:
     ```xml
     <ActiveParticipant UserID="★user_id" NetworkAccessPointID="★nap_id" NetworkAccessPointTypeCode="★nap_type" UserIsRequest="false">
@@ -85,6 +86,11 @@ Then, two _ActiveParticipants_ describe the source and destination participants.
     
     Other attributes are optional.
 
+!!! warning
+    In some transactions such as ITI-43, the source and destination participants are reversed. Always check the IHE 
+    specifications for the correct order. The participant "server" is the one having the "SOAP endpoint URI", the 
+    participant "client" is the one having the "process ID".
+
 Following that is the `#!xml <AuditSourceIdentification>` element.
 It contains the following:
 ```xml