docs(dcl): M2.13 review nits — OriginalRaiseTime ConditionRefresh/UTC caveats + Description-vs-Message note (#27)

src/ZB.MOM.WW.ScadaBridge.DataConnectionLayer/Adapters/RealOpcUaClient.cs

@@ -398,7 +398,11 @@ public class RealOpcUaClient : IOpcUaClient
 
         // 13: AlarmConditionType/ActiveState/TransitionTime — the UTC instant the active-state
         //     last flipped to TRUE.  Mapped to OriginalRaiseTime; absent on non-AlarmCondition
-        //     events (ConditionType base events rarely carry it).
+        //     events (ConditionType base events rarely carry it).  CAVEAT: during a
+        //     ConditionRefresh replay the server MAY re-stamp this to the current/restart time
+        //     rather than the historical raise instant (OPC UA Part 9 §5.5.2 makes it advisory),
+        //     so a snapshot-derived OriginalRaiseTime can look like the refresh time — it is
+        //     display-only and not treated as authoritative.
         filter.SelectClauses.Add(SelectField(ObjectTypeIds.AlarmConditionType, "ActiveState", "TransitionTime")); // 13
 
         // 14–17: LimitAlarmType limit thresholds — configuration-time set-points exposed as
@@ -413,8 +417,9 @@ public class RealOpcUaClient : IOpcUaClient
         // UNAVAILABLE via standard OPC UA A&C event fields (documented here so future
         // maintainers know these were considered, not overlooked):
         //   Category     — not a standard event field; server-specific extensions only.
-        //   Description  — not a per-event text field; the OPC UA Description attribute is a
-        //                  static node property, not carried in event notifications.
+        //   Description  — NativeAlarmTransition.Description is a static template description;
+        //                  OPC UA events carry dynamic Message text (index 4, mapped) but no
+        //                  static template description in the notification, so this stays empty.
         //   OperatorUser — not available on the standard ConditionRefresh replay stream;
         //                  present on Acknowledge/Confirm method call results, but those do
         //                  not flow through the monitored-item subscription.
@@ -539,6 +544,8 @@ public class RealOpcUaClient : IOpcUaClient
         // transitioned to TRUE).  Absent on non-AlarmCondition events → guard + null fallback.
         DateTimeOffset? originalRaiseTime = null;
         if (fields.Count > 13 && fields[13].Value is DateTime activeTransitionTime)
+            // OPC UA mandates UTC for DateTime fields; a TimeSpan.Zero offset treats an
+            // Unspecified Kind as UTC (consistent with the Time→TransitionTime mapping above).
             originalRaiseTime = new DateTimeOffset(activeTransitionTime, TimeSpan.Zero);
 
         // Indices 14–17: LimitAlarmType set-point thresholds (HighHighLimit/HighLimit/