Here is a list of all documented functions, variables, defines, enums, and typedefs with links to the documentation:

### - i -

- I2A : tgp.cpp
- I2H : tgp.cpp
- IACT_MAPGENERATION : newgrf_industries.h
- IACT_RANDOMCREATION : newgrf_industries.h
- IACT_USERCREATION : newgrf_industries.h
- ICON_CMDLN_SIZE : console_internal.h
- ICON_MAX_STREAMSIZE : console_internal.h
- IConsoleAddSorted : console.cpp
- IConsoleAliasExec() : console.cpp
- IConsoleAliasGet() : console.cpp , console_internal.h
- IConsoleAliasRegister() : console.cpp , console_internal.h
- IConsoleCmdExec() : console.cpp , console_func.h
- IConsoleCmdGet() : console.cpp , console_internal.h
- IConsoleCmdProc : console_internal.h
- IConsoleCmdRegister() : console.cpp , console_internal.h
- IConsoleCopyInParams() : console.cpp
- IConsoleDebug() : console.cpp , console_func.h
- IConsoleError() : console.cpp , console_func.h
- IConsoleGetSetting() : settings.cpp , settings_func.h
- IConsoleGUIPrint() : console_gui.cpp , console_internal.h
- IConsoleHistoryAdd() : console_gui.cpp
- IConsoleHistoryNavigate() : console_gui.cpp
- IConsoleListSettings() : settings.cpp , settings_func.h
- IConsolePrint() : console.cpp , console_func.h
- IConsolePrintF() : console.cpp
- IConsoleWarning() : console.cpp , console_func.h
- ICT_MAP_GENERATION : industrytype.h
- ICT_NORMAL_GAMEPLAY : industrytype.h
- ICT_SCENARIO_EDITOR : industrytype.h
- ICT_UNKNOWN : industrytype.h
- Ignore : depend.cpp
- IGNORE_UNTIL_ELSE : depend.cpp
- IGNORE_UNTIL_ENDIF : depend.cpp
- IgnoredPCP : elrail_data.h
- IGT_LIST : ini_type.h
- IGT_VARIABLES : ini_type.h
- IncHouseConstructionTick() : town_map.h
- IncIndustryTypeCount() : industrytype.h
- InclinedFoundation() : slope_func.h
- InclinedSlope() : slope_func.h
- IncreaseBuildingCount() : newgrf_house.cpp , newgrf_house.h
- IncreaseCompanyManagerFaceBits() : company_manager_face.h
- IncreaseDate() : date.cpp , openttd.cpp
- IncreaseGeneratingWorldProgress() : genworld.h , genworld_gui.cpp
- IncrementHouseAge() : town_map.h
- INDTILE_SPECIAL_NEXTFRAME_RANDOMBITS : industrytype.h
- INDUSTRY_COMPLETED : industry_type.h
- INDUSTRY_TRIGGER_256_TICKS : newgrf_industries.h
- INDUSTRY_TRIGGER_CARGO_DELIVERY : newgrf_industries.h
- INDUSTRY_TRIGGER_TILELOOP_PROCESS : newgrf_industries.h
- IndustryAvailabilityCallType : newgrf_industries.h
- INDUSTRYBEH_AFTER_1960 : industrytype.h
- INDUSTRYBEH_AI_AIRSHIP_ROUTES : industrytype.h
- INDUSTRYBEH_AIRPLANE_ATTACKS : industrytype.h
- INDUSTRYBEH_BEFORE_1950 : industrytype.h
- INDUSTRYBEH_BUILT_ONWATER : industrytype.h
- INDUSTRYBEH_CAN_SUBSIDENCE : industrytype.h
- INDUSTRYBEH_CANCLOSE_LASTINSTANCE : industrytype.h
- INDUSTRYBEH_CHOPPER_ATTACKS : industrytype.h
- INDUSTRYBEH_CUT_TREES : industrytype.h
- INDUSTRYBEH_DONT_INCR_PROD : industrytype.h
- INDUSTRYBEH_NOBUILT_MAPCREATION : industrytype.h
- INDUSTRYBEH_ONLY_INTOWN : industrytype.h
- INDUSTRYBEH_ONLY_NEARTOWN : industrytype.h
- INDUSTRYBEH_PLANT_FIELDS : industrytype.h
- INDUSTRYBEH_PLANT_ON_BUILT : industrytype.h
- INDUSTRYBEH_PROD_MULTI_HNDLING : industrytype.h
- INDUSTRYBEH_PRODCALLBACK_RANDOM : industrytype.h
- INDUSTRYBEH_TOWN1200_MORE : industrytype.h
- IndustryBehaviour : industrytype.h
- IndustryCallbackMask : newgrf_callbacks.h
- IndustryConstructionType : industrytype.h
- IndustryDailyLoop() : date.cpp , industry_cmd.cpp
- IndustryDirectoryWidgets : industry_gui.cpp
- IndustryGetVariable() : newgrf_industries.cpp , newgrf_industries.h
- IndustryID : ai_types.hpp
- INDUSTRYLIFE_BLACK_HOLE : industrytype.h
- INDUSTRYLIFE_EXTRACTIVE : industrytype.h
- INDUSTRYLIFE_ORGANIC : industrytype.h
- INDUSTRYLIFE_PROCESSING : industrytype.h
- IndustryLifeType : industrytype.h
- IndustryProductionCallback() : newgrf_industries.cpp , newgrf_industries.h
- INDUSTRYTILE_NOANIM : industry_type.h
- IndustryTileCallbackMask : newgrf_callbacks.h
- IndustryTileSpecialFlags : industrytype.h
- IndustryTrigger : newgrf_industries.h
- IndustryType : ai_types.hpp
- IndustryViewWidgets : industry_gui.cpp
- ini_load_setting_list() : settings.cpp
- ini_load_settings() : settings.cpp
- ini_save_setting_list() : settings.cpp
- ini_save_settings() : settings.cpp
- IniGroupType : ini_type.h
- init_BinaryHeap() : queue.cpp , queue.h
- init_Hash() : queue.cpp , queue.h
- init_InsSort() : queue.cpp , queue.h
- InitDepotWindowBlockSizes() : depot_gui.cpp , newgrf.cpp
- InitializeAIGui() : ai_gui.cpp , ai_gui.hpp
- InitializeAnimatedTiles() : animated_tile.cpp , animated_tile_func.h
- InitializeCargoPackets() : cargopacket.cpp , misc.cpp
- InitializeDisasterVehicle() : disaster_cmd.cpp
- InitializeEconomy() : economy_func.h , economy.cpp
- InitializeLanguagePacks() : strings.cpp , strings_func.h
- InitializeMusic() : misc.cpp , music_gui.cpp
- InitializeNetworkPools() : network.cpp
- InitializeOldNames() : misc.cpp , saveload_internal.h , strings_sl.cpp
- InitializeRailGUI() : openttd.cpp , rail_gui.cpp , afterload.cpp
- InitializeRailGui() : misc.cpp , rail_gui.cpp
- InitializeSigns() : misc.cpp , signs.cpp
- InitializeSubsidies() : misc.cpp , subsidy.cpp
- InitializeTextBuffer() : misc_gui.cpp , textbuf_gui.h
- InitializeUnicodeGlyphMap() : fontcache.cpp , fontcache.h
- InitializeWindowsAndCaches() : afterload.cpp
- InitializeWindowViewport() : viewport.cpp , viewport_func.h
- InitLoading() : oldloader.cpp
- InitNewsItemStructs() : news_func.h , news_gui.cpp
- InitQuickTimeIfNeeded() : qtmidi.cpp
- InitRailTypes() : rail.h , rail_cmd.cpp
- InitWindowSystem() : window.cpp , window_func.h
- InjectDParam() : strings.cpp , strings_func.h
- InputLoop() : window.cpp , window_func.h
- InsertInConsist() : train_cmd.cpp
- InsertTextBufferChar() : misc_gui.cpp
- InsertTextBufferClipboard() : misc_gui.cpp , textbuf_gui.h
- INSTANTIATE_BASE_MEDIA_METHODS : base_media_func.h
- INSTANTIATE_POOL_METHODS : pool_func.hpp
- int_noise() : tgp.cpp
- interpolated_noise() : tgp.cpp
- IntToReference() : saveload.cpp
- INVALID_AXIS : direction_type.h
- INVALID_CARGO : cargotype.h
- INVALID_CLIENT_ID : network_type.h
- INVALID_COMPANY : company_type.h
- INVALID_DATE : date_type.h
- INVALID_DIAGDIR : direction_type.h
- INVALID_DIR : direction_type.h
- INVALID_EXPENSES : economy_type.h
- INVALID_INDUSTRYTILE : industry_type.h
- INVALID_INDUSTRYTYPE : industry_type.h
- INVALID_ORDER : order_type.h
- INVALID_OWNER : company_type.h
- INVALID_RAILTYPE : rail_type.h
- INVALID_RAILTYPES : rail_type.h
- INVALID_ROADTYPE : road_type.h
- INVALID_ROADTYPES : road_type.h
- INVALID_SOURCE : cargo_type.h
- INVALID_STRING_ID : strings_type.h
- INVALID_TICKS : date_type.h
- INVALID_TILE : tile_type.h
- INVALID_TRACK : track_type.h
- INVALID_TRACK_BIT : track_type.h
- INVALID_TRACKDIR : track_type.h
- INVALID_TRACKDIR_BIT : track_type.h
- INVALID_VEH_ORDER_ID : order_type.h
- INVALID_VEHICLE : vehicle_type.h
- INVALID_YEAR : date_type.h
- InvalidateAutoreplaceWindow() : autoreplace_gui.cpp , autoreplace_gui.h
- InvalidateVehicleOrder() : order_cmd.cpp , order_func.h
- InvalidateWindowClassesData() : window.cpp , window_func.h
- InvalidateWindowData() : window.cpp , window_func.h
- InverseRemapCoords() : landscape.h
- IS_PALETTE_COLOUR : gfx_type.h
- IsAirport() : station_map.h
- IsAirportTile() : station_map.h
- IsAllGroupID() : group.h
- IsArticulatedVehicleCarryingDifferentCargos() : articulated_vehicles.h , articulated_vehicles.cpp
- IsArticulatedVehicleRefittable() : articulated_vehicles.cpp , articulated_vehicles.h
- IsBridge() : bridge_map.h
- IsBridgeAbove() : bridge_map.h
- IsBridgeTile() : bridge_map.h
- IsBuoy() : station_map.h
- IsBuoyTile() : station_map.h
- IsBusStop() : station_map.h
- IsCargoInClass() : cargotype.h
- IsClearGround() : clear_map.h
- IsCloseToTown() : town_cmd.cpp
- IsCompanyHQ() : unmovable_map.h
- IsCompatibleRail() : rail.h
- IsCompatibleTrainStationTile() : station_map.h
- IsCustomStationSpecIndex() : station_map.h
- IsDepotTile() : depot_map.h
- IsDepotTypeTile() : depot_map.h
- IsDiagonalTrack() : track_func.h
- IsDiagonalTrackdir() : track_func.h
- IsDock() : station_map.h
- IsDockTile() : station_map.h
- IsDriveThroughStopTile() : station_map.h
- IsEngineBuildable() : engine_func.h , engine.cpp
- IsEngineRefittable() : engine.cpp , engine_func.h
- IsFoundation() : slope_func.h
- IsGenerateWorldThreaded() : genworld.cpp , genworld.h
- IsGeneratingWorld() : genworld.h
- IsGeneratingWorldAborted() : genworld.cpp , genworld.h
- IsGoodAutoPlace1() : window.cpp
- IsGoodAutoPlace2() : window.cpp
- IsGoodGRFConfigList() : newgrf_config.h , newgrf_config.cpp
- IsHalftileSlope() : slope_func.h
- IsHangar() : station_cmd.cpp , station_map.h
- IsHangarTile() : station_map.h
- IsHouseCompleted() : town_map.h
- IsHouseSpecValid() : newgrf.cpp
- IsInclinedFoundation() : slope_func.h
- IsInclinedSlope() : slope_func.h
- IsIndustryCompleted() : industry_map.h
- IsIndustryTileOnWater() : industry_map.h
- IsInsideBS() : math_func.hpp
- IsInsideMM() : math_func.hpp
- IsInvisibilitySet() : transparency.h
- IsLeveledFoundation() : slope_func.h
- IsLoggableGrfConfig() : gamelog.cpp
- IsNeighborRoadTile() : town_cmd.cpp
- IsNetworkCompatibleVersion() : network.cpp , network_internal.h
- IsNewsTickerShown() : statusbar_gui.h , statusbar_gui.cpp
- IsNonContinuousFoundation() : slope_func.h
- IsNumericType() : saveload.h
- IsOilRig() : station_map.h
- IsOnewaySignal() : rail_map.h
- IsOwnedLand() : unmovable_map.h
- IsOwnedLandTile() : unmovable_map.h
- IsPlainRail() : rail_map.h
- IsPlainRailTile() : rail_map.h
- IsPossibleCrossing() : road.cpp
- IsPtInWindowViewport() : viewport.cpp , viewport_func.h
- IsRailDepot() : rail_map.h
- IsRailDepotTile() : rail_map.h
- IsRailStation() : station_map.h
- IsRailStationTile() : station_map.h
- IsRailWaypoint() : station_map.h
- IsRailWaypointTile() : station_map.h
- IsReversingRoadTrackdir() : track_func.h
- IsRoadAllowedHere() : town_cmd.cpp
- IsRoadStop() : station_map.h
- IsRoadStopTile() : station_map.h
- IsSafeWaitingPosition() : pbs.cpp , pbs.h
- IsSameAI() : ai_scanner.cpp
- IsSignalPresent() : rail_map.h
- IsSlopeWithOneCornerRaised() : slope_func.h
- IsSlopeWithThreeCornersRaised() : slope_func.h
- IsSnowLineSet() : landscape.h , landscape.cpp
- IsSnowTile() : clear_map.h
- IsSpecialRailFoundation() : slope_func.h
- IsStandardRoadStopTile() : station_map.h
- IsStatue() : unmovable_map.h
- IsStatueTile() : unmovable_map.h
- IsSteepSlope() : slope_func.h
- IsStraightRoad() : road_func.h
- IsStraightRoadTrackdir() : track_func.h
- IsTextDirectionChar() : string_func.h
- IsTileAlignedToGrid() : town_cmd.cpp
- IsTileOwner() : tile_map.h
- IsTileType() : tile_map.h
- IsTransmitterTile() : unmovable_map.h
- IsTransparencySet() : transparency.h
- IsTruckStop() : station_map.h
- IsTunnel() : tunnel_map.h
- IsTunnelInWay() : tunnel_map.cpp , tunnel_map.h
- IsTunnelInWayDir() : tunnel_map.cpp , tunnel_map.h
- IsTunnelTile() : tunnel_map.h
- IsUniqueTownName() : town_cmd.cpp
- IsUniqueVehicleName() : vehicle_cmd.cpp
- IsUphillTrackdir() : track_func.h
- IsValidAxis() : direction_func.h
- IsValidChar() : string_func.h , string.cpp
- IsValidCommand() : command_func.h , command.cpp
- IsValidCompanyManagerFace() : company_cmd.cpp , company_manager_face.h
- IsValidCorner() : slope_func.h
- IsValidDiagDirection() : direction_func.h
- IsValidDirection() : direction_func.h
- IsValidRoadType() : road_func.h
- IsValidSearchPath() : fileio_func.h
- IsValidSignalType() : ai_rail.cpp
- IsValidTile() : tile_map.h
- IsValidTileForWaypoint() : waypoint_cmd.cpp
- IsValidTrack() : track_func.h
- IsValidTrackdir() : track_func.h
- IsValidXY() : tgp.cpp
- IsVehicleRefitable() : vehicle_gui.cpp
- IsWaitingPositionFree() : pbs.h , pbs.cpp
- IsWater() : water_map.h
- IsWateredTile() : water_cmd.cpp
- IsWhitespace() : string_func.h
- ItemAtT() : dbg_helpers.h