diff --git a/ai/compat_1.0.nut b/ai/compat_1.0.nut
new file mode 100644
--- /dev/null
+++ b/ai/compat_1.0.nut
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+/*
+ * This file is part of OpenTTD.
+ * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
+ * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+AILog.Info("1.0 API compatibility in effect.");
+
+AIRoad._BuildRoadStation <- AIRoad.BuildRoadStation;
+AIRoad.BuildRoadStation <- function(tile, front, road_veh_type, station_id)
+{
+	if (AIRoad.IsRoadStationTile(tile) && AICompany.IsMine(AITile.GetOwner(tile))) return false;
+
+	return AIRoad._BuildRoadStation(tile, front, road_veh_type, station_id);
+}
+
+AIRoad._BuildDriveThroughRoadStation <- AIRoad.BuildDriveThroughRoadStation;
+AIRoad.BuildDriveThroughRoadStation <- function(tile, front, road_veh_type, station_id)
+{
+	if (AIRoad.IsRoadStationTile(tile) && AICompany.IsMine(AITile.GetOwner(tile))) return false;
+
+	return AIRoad._BuildDriveThroughRoadStation(tile, front, road_veh_type, station_id);
+}
+
+AIBridgeList.HasNext <-
+AIBridgeList_Length.HasNext <-
+AICargoList.HasNext <-
+AICargoList_IndustryAccepting.HasNext <-
+AICargoList_IndustryProducing.HasNext <-
+AIDepotList.HasNext <-
+AIEngineList.HasNext <-
+AIGroupList.HasNext <-
+AIIndustryList.HasNext <-
+AIIndustryList_CargoAccepting.HasNext <-
+AIIndustryList_CargoProducing.HasNext <-
+AIIndustryTypeList.HasNext <-
+AIList.HasNext <-
+AIRailTypeList.HasNext <-
+AISignList.HasNext <-
+AIStationList.HasNext <-
+AIStationList_Vehicle.HasNext <-
+AISubsidyList.HasNext <-
+AITileList.HasNext <-
+AITileList_IndustryAccepting.HasNext <-
+AITileList_IndustryProducing.HasNext <-
+AITileList_StationType.HasNext <-
+AITownList.HasNext <-
+AIVehicleList.HasNext <-
+AIVehicleList_DefaultGroup.HasNext <-
+AIVehicleList_Depot.HasNext <-
+AIVehicleList_Group.HasNext <-
+AIVehicleList_SharedOrders.HasNext <-
+AIVehicleList_Station.HasNext <-
+AIWaypointList.HasNext <-
+AIWaypointList_Vehicle.HasNext <-
+function()
+{
+	return !this.IsEnd();
+}
+
+AIIndustry._IsCargoAccepted <- AIIndustry.IsCargoAccepted;
+AIIndustry.IsCargoAccepted <- function(industry_id, cargo_id)
+{
+	return AIIndustry._IsCargoAccepted(industry_id, cargo_id) != AIIndustry.CAS_NOT_ACCEPTED;
+}
+
+AIAbstractList <- AIList;
+
+AIList.ChangeItem <- AIList.SetValue;
+
+AIRail.ERR_NONUNIFORM_STATIONS_DISABLED <- 0xFFFF;
+
+AICompany.GetCompanyValue <- function(company)
+{
+	return AICompany.GetQuarterlyCompanyValue(company, AICompany.CURRENT_QUARTER);
+}
+
+AITown.GetLastMonthTransported <- AITown.GetLastMonthSupplied;
+
+AIEvent.AI_ET_INVALID <- AIEvent.ET_INVALID;
+AIEvent.AI_ET_TEST <- AIEvent.ET_TEST;
+AIEvent.AI_ET_SUBSIDY_OFFER <- AIEvent.ET_SUBSIDY_OFFER;
+AIEvent.AI_ET_SUBSIDY_OFFER_EXPIRED <- AIEvent.ET_SUBSIDY_OFFER_EXPIRED;
+AIEvent.AI_ET_SUBSIDY_AWARDED <- AIEvent.ET_SUBSIDY_AWARDED;
+AIEvent.AI_ET_SUBSIDY_EXPIRED <- AIEvent.ET_SUBSIDY_EXPIRED;
+AIEvent.AI_ET_ENGINE_PREVIEW <- AIEvent.ET_ENGINE_PREVIEW;
+AIEvent.AI_ET_COMPANY_NEW <- AIEvent.ET_COMPANY_NEW;
+AIEvent.AI_ET_COMPANY_IN_TROUBLE <- AIEvent.ET_COMPANY_IN_TROUBLE;
+AIEvent.AI_ET_COMPANY_ASK_MERGER <- AIEvent.ET_COMPANY_ASK_MERGER;
+AIEvent.AI_ET_COMPANY_MERGER <- AIEvent.ET_COMPANY_MERGER;
+AIEvent.AI_ET_COMPANY_BANKRUPT <- AIEvent.ET_COMPANY_BANKRUPT;
+AIEvent.AI_ET_VEHICLE_CRASHED <- AIEvent.ET_VEHICLE_CRASHED;
+AIEvent.AI_ET_VEHICLE_LOST <- AIEvent.ET_VEHICLE_LOST;
+AIEvent.AI_ET_VEHICLE_WAITING_IN_DEPOT <- AIEvent.ET_VEHICLE_WAITING_IN_DEPOT;
+AIEvent.AI_ET_VEHICLE_UNPROFITABLE <- AIEvent.ET_VEHICLE_UNPROFITABLE;
+AIEvent.AI_ET_INDUSTRY_OPEN <- AIEvent.ET_INDUSTRY_OPEN;
+AIEvent.AI_ET_INDUSTRY_CLOSE <- AIEvent.ET_INDUSTRY_CLOSE;
+AIEvent.AI_ET_ENGINE_AVAILABLE <- AIEvent.ET_ENGINE_AVAILABLE;
+AIEvent.AI_ET_STATION_FIRST_VEHICLE <- AIEvent.ET_STATION_FIRST_VEHICLE;
+AIEvent.AI_ET_DISASTER_ZEPPELINER_CRASHED <- AIEvent.ET_DISASTER_ZEPPELINER_CRASHED;
+AIEvent.AI_ET_DISASTER_ZEPPELINER_CLEARED <- AIEvent.ET_DISASTER_ZEPPELINER_CLEARED;
+AIOrder.AIOF_NONE <- AIOrder.OF_NONE
+AIOrder.AIOF_NON_STOP_INTERMEDIATE <- AIOrder.OF_NON_STOP_INTERMEDIATE
+AIOrder.AIOF_NON_STOP_DESTINATION <- AIOrder.OF_NON_STOP_DESTINATION
+AIOrder.AIOF_UNLOAD <- AIOrder.OF_UNLOAD
+AIOrder.AIOF_TRANSFER <- AIOrder.OF_TRANSFER
+AIOrder.AIOF_NO_UNLOAD <- AIOrder.OF_NO_UNLOAD
+AIOrder.AIOF_FULL_LOAD <- AIOrder.OF_FULL_LOAD
+AIOrder.AIOF_FULL_LOAD_ANY <- AIOrder.OF_FULL_LOAD_ANY
+AIOrder.AIOF_NO_LOAD <- AIOrder.OF_NO_LOAD
+AIOrder.AIOF_SERVICE_IF_NEEDED <- AIOrder.OF_SERVICE_IF_NEEDED
+AIOrder.AIOF_STOP_IN_DEPOT <- AIOrder.OF_STOP_IN_DEPOT
+AIOrder.AIOF_GOTO_NEAREST_DEPOT <- AIOrder.OF_GOTO_NEAREST_DEPOT
+AIOrder.AIOF_NON_STOP_FLAGS <- AIOrder.OF_NON_STOP_FLAGS
+AIOrder.AIOF_UNLOAD_FLAGS <- AIOrder.OF_UNLOAD_FLAGS
+AIOrder.AIOF_LOAD_FLAGS <- AIOrder.OF_LOAD_FLAGS
+AIOrder.AIOF_DEPOT_FLAGS <- AIOrder.OF_DEPOT_FLAGS
+AIOrder.AIOF_INVALID <- AIOrder.OF_INVALID
+
+/* 1.9 adds a vehicle type parameter. */
+AIBridge._GetName <- AIBridge.GetName;
+AIBridge.GetName <- function(bridge_id)
+{
+	return AIBridge._GetName(bridge_id, AIVehicle.VT_RAIL);
+}
+
+/* 1.9 adds parent_group_id to CreateGroup function */
+AIGroup._CreateGroup <- AIGroup.CreateGroup;
+AIGroup.CreateGroup <- function(vehicle_type)
+{
+	return AIGroup._CreateGroup(vehicle_type, AIGroup.GROUP_INVALID);
+}