diff --git a/protos/stationLayoutGraphics.proto b/protos/stationLayoutGraphics.proto
index f1c0501..b0de0cf 100644
--- a/protos/stationLayoutGraphics.proto
+++ b/protos/stationLayoutGraphics.proto
@@ -473,6 +473,7 @@ message CalculateLink {
 message UniqueIdOfStationLayout {
   string city = 1;//城市
   string lineId = 2;//线路号
+  string mainCoordinateSystem = 3;//地图的公里标主坐标系
 }
 
 //公里标转换