diff --git a/protos/stationLayoutGraphics.proto b/protos/stationLayoutGraphics.proto
index 557376f..bd1236b 100644
--- a/protos/stationLayoutGraphics.proto
+++ b/protos/stationLayoutGraphics.proto
@@ -234,11 +234,12 @@ message SectionLink {
   CommonInfo common = 1;
   string code = 2;
   repeated Point points = 3;
-  bool up = 4;
-  SimpleRef aSimRef = 5;
-  SimpleRef bSimRef = 6;
-  RelatedRef aRef = 7;
-  RelatedRef bRef = 8;
+  bool up = 4; // 是否上行
+  SimpleRef aSimRef = 5; // SectionLink A端连接设备（构建关系 AxleCounting/Turnout）
+  SimpleRef bSimRef = 6; // SectionLink B端连接设备（构建关系 AxleCounting/Turnout）
+  RelatedRef aRef = 7; // SectionLink A端连接设备（端口关系 SectionLink/Turnout）
+  RelatedRef bRef = 8; //SectionLink B端连接设备（端口关系 SectionLink/Turnout）
+  int32 index = 9; // 索引编号
 }
 
 message AxleCountingSection { // 计轴区段