diff --git a/src/console_cmds.cpp b/src/console_cmds.cpp
index 863929b94c..9cfc8e8f9d 100644
--- a/src/console_cmds.cpp
+++ b/src/console_cmds.cpp
@@ -67,7 +67,7 @@ public:
 	void ValidateFileList(bool force_reload = false)
 	{
 		if (force_reload || !this->file_list_valid) {
-			this->BuildFileList(FT_SAVEGAME, FOP_LOAD);
+			this->BuildFileList(FT_SAVEGAME, SLO_LOAD);
 			this->file_list_valid = true;
 		}
 	}
@@ -318,7 +318,7 @@ DEF_CONSOLE_CMD(ConSave)
 		char *filename = str_fmt("%s.sav", argv[1]);
 		IConsolePrint(CC_DEFAULT, "Saving map...");
 
-		if (SaveOrLoad(filename, FOP_SAVE, DFT_GAME_FILE, SAVE_DIR) != SL_OK) {
+		if (SaveOrLoad(filename, SLO_SAVE, DFT_GAME_FILE, SAVE_DIR) != SL_OK) {
 			IConsolePrint(CC_ERROR, "Saving map failed");
 		} else {
 			IConsolePrintF(CC_DEFAULT, "Map successfully saved to %s", filename);
diff --git a/src/crashlog.cpp b/src/crashlog.cpp
index 83beb94ff8..53a85e442c 100644
--- a/src/crashlog.cpp
+++ b/src/crashlog.cpp
@@ -388,7 +388,7 @@ bool CrashLog::WriteSavegame(char *filename, const char *filename_last) const
 		seprintf(filename, filename_last, "%scrash.sav", _personal_dir);
 
 		/* Don't do a threaded saveload. */
-		return SaveOrLoad(filename, FOP_SAVE, DFT_GAME_FILE, NO_DIRECTORY, false) == SL_OK;
+		return SaveOrLoad(filename, SLO_SAVE, DFT_GAME_FILE, NO_DIRECTORY, false) == SL_OK;
 	} catch (...) {
 		return false;
 	}
diff --git a/src/fileio_type.h b/src/fileio_type.h
index 0c4602bbaf..fd3ac84554 100644
--- a/src/fileio_type.h
+++ b/src/fileio_type.h
@@ -46,12 +46,12 @@ enum DetailedFileType {
 };
 
 /** Operation performed on the file. */
-enum FileOperation {
-	FOP_CHECK,   ///< Load file for checking and/or preview.
-	FOP_LOAD,    ///< File is being loaded.
-	FOP_SAVE,    ///< File is being saved.
+enum SaveLoadOperation {
+	SLO_CHECK,   ///< Load file for checking and/or preview.
+	SLO_LOAD,    ///< File is being loaded.
+	SLO_SAVE,    ///< File is being saved.
 
-	FOP_INVALID, ///< Unknown file operation.
+	SLO_INVALID, ///< Unknown file operation.
 };
 
 /**
diff --git a/src/fios.cpp b/src/fios.cpp
index 987542acc9..8ed01152f0 100644
--- a/src/fios.cpp
+++ b/src/fios.cpp
@@ -71,13 +71,13 @@ FileList::~FileList()
 /**
  * Construct a file list with the given kind of files, for the stated purpose.
  * @param abstract_filetype Kind of files to collect.
- * @param fop Purpose of the collection, either #FOP_LOAD or #FOP_SAVE.
+ * @param fop Purpose of the collection, either #SLO_LOAD or #SLO_SAVE.
  */
-void FileList::BuildFileList(AbstractFileType abstract_filetype, FileOperation fop)
+void FileList::BuildFileList(AbstractFileType abstract_filetype, SaveLoadOperation fop)
 {
 	this->Clear();
 
-	assert(fop == FOP_LOAD || FOP_SAVE);
+	assert(fop == SLO_LOAD || SLO_SAVE);
 	switch (abstract_filetype) {
 		case FT_NONE:
 			break;
@@ -274,13 +274,13 @@ bool FiosDelete(const char *name)
 	return unlink(filename) == 0;
 }
 
-typedef FiosType fios_getlist_callback_proc(FileOperation fop, const char *filename, const char *ext, char *title, const char *last);
+typedef FiosType fios_getlist_callback_proc(SaveLoadOperation fop, const char *filename, const char *ext, char *title, const char *last);
 
 /**
  * Scanner to scan for a particular type of FIOS file.
  */
 class FiosFileScanner : public FileScanner {
-	FileOperation fop;       ///< The kind of file we are looking for.
+	SaveLoadOperation fop;   ///< The kind of file we are looking for.
 	fios_getlist_callback_proc *callback_proc; ///< Callback to check whether the file may be added
 	FileList &file_list;     ///< Destination of the found files.
 public:
@@ -290,7 +290,7 @@ public:
 	 * @param callback_proc The function that is called where you need to do the filtering.
 	 * @param file_list Destination of the found files.
 	 */
-	FiosFileScanner(FileOperation fop, fios_getlist_callback_proc *callback_proc, FileList &file_list) :
+	FiosFileScanner(SaveLoadOperation fop, fios_getlist_callback_proc *callback_proc, FileList &file_list) :
 			fop(fop), callback_proc(callback_proc), file_list(file_list)
 	{}
 
@@ -354,7 +354,7 @@ bool FiosFileScanner::AddFile(const char *filename, size_t basepath_length, cons
  * @param subdir The directory from where to start (global) searching.
  * @param file_list Destination of the found files.
  */
-static void FiosGetFileList(FileOperation fop, fios_getlist_callback_proc *callback_proc, Subdirectory subdir, FileList &file_list)
+static void FiosGetFileList(SaveLoadOperation fop, fios_getlist_callback_proc *callback_proc, Subdirectory subdir, FileList &file_list)
 {
 	struct stat sb;
 	struct dirent *dirent;
@@ -456,7 +456,7 @@ static void GetFileTitle(const char *file, char *title, const char *last, Subdir
  * @see FiosGetFileList
  * @see FiosGetSavegameList
  */
-FiosType FiosGetSavegameListCallback(FileOperation fop, const char *file, const char *ext, char *title, const char *last)
+FiosType FiosGetSavegameListCallback(SaveLoadOperation fop, const char *file, const char *ext, char *title, const char *last)
 {
 	/* Show savegame files
 	 * .SAV OpenTTD saved game
@@ -472,7 +472,7 @@ FiosType FiosGetSavegameListCallback(FileOperation fop, const char *file, const
 		return FIOS_TYPE_FILE;
 	}
 
-	if (fop == FOP_LOAD) {
+	if (fop == SLO_LOAD) {
 		if (strcasecmp(ext, ".ss1") == 0 || strcasecmp(ext, ".sv1") == 0 ||
 				strcasecmp(ext, ".sv2") == 0) {
 			if (title != NULL) GetOldSaveGameName(file, title, last);
@@ -489,7 +489,7 @@ FiosType FiosGetSavegameListCallback(FileOperation fop, const char *file, const
  * @param file_list Destination of the found files.
  * @see FiosGetFileList
  */
-void FiosGetSavegameList(FileOperation fop, FileList &file_list)
+void FiosGetSavegameList(SaveLoadOperation fop, FileList &file_list)
 {
 	static char *fios_save_path = NULL;
 	static char *fios_save_path_last = NULL;
@@ -517,7 +517,7 @@ void FiosGetSavegameList(FileOperation fop, FileList &file_list)
  * @see FiosGetFileList
  * @see FiosGetScenarioList
  */
-static FiosType FiosGetScenarioListCallback(FileOperation fop, const char *file, const char *ext, char *title, const char *last)
+static FiosType FiosGetScenarioListCallback(SaveLoadOperation fop, const char *file, const char *ext, char *title, const char *last)
 {
 	/* Show scenario files
 	 * .SCN OpenTTD style scenario file
@@ -528,7 +528,7 @@ static FiosType FiosGetScenarioListCallback(FileOperation fop, const char *file,
 		return FIOS_TYPE_SCENARIO;
 	}
 
-	if (fop == FOP_LOAD) {
+	if (fop == SLO_LOAD) {
 		if (strcasecmp(ext, ".sv0") == 0 || strcasecmp(ext, ".ss0") == 0 ) {
 			GetOldSaveGameName(file, title, last);
 			return FIOS_TYPE_OLD_SCENARIO;
@@ -544,7 +544,7 @@ static FiosType FiosGetScenarioListCallback(FileOperation fop, const char *file,
  * @param file_list Destination of the found files.
  * @see FiosGetFileList
  */
-void FiosGetScenarioList(FileOperation fop, FileList &file_list)
+void FiosGetScenarioList(SaveLoadOperation fop, FileList &file_list)
 {
 	static char *fios_scn_path = NULL;
 	static char *fios_scn_path_last = NULL;
@@ -562,11 +562,11 @@ void FiosGetScenarioList(FileOperation fop, FileList &file_list)
 	char base_path[MAX_PATH];
 	FioGetDirectory(base_path, lastof(base_path), SCENARIO_DIR);
 
-	Subdirectory subdir = (fop == FOP_LOAD && strcmp(base_path, _fios_path) == 0) ? SCENARIO_DIR : NO_DIRECTORY;
+	Subdirectory subdir = (fop == SLO_LOAD && strcmp(base_path, _fios_path) == 0) ? SCENARIO_DIR : NO_DIRECTORY;
 	FiosGetFileList(fop, &FiosGetScenarioListCallback, subdir, file_list);
 }
 
-static FiosType FiosGetHeightmapListCallback(FileOperation fop, const char *file, const char *ext, char *title, const char *last)
+static FiosType FiosGetHeightmapListCallback(SaveLoadOperation fop, const char *file, const char *ext, char *title, const char *last)
 {
 	/* Show heightmap files
 	 * .PNG PNG Based heightmap files
@@ -615,7 +615,7 @@ static FiosType FiosGetHeightmapListCallback(FileOperation fop, const char *file
  * @param fop Purpose of collecting the list.
  * @param file_list Destination of the found files.
  */
-void FiosGetHeightmapList(FileOperation fop, FileList &file_list)
+void FiosGetHeightmapList(SaveLoadOperation fop, FileList &file_list)
 {
 	static char *fios_hmap_path = NULL;
 	static char *fios_hmap_path_last = NULL;
diff --git a/src/fios.h b/src/fios.h
index 80654812b2..51e0c275a6 100644
--- a/src/fios.h
+++ b/src/fios.h
@@ -190,7 +190,7 @@ public:
 		this->files.Compact();
 	}
 
-	void BuildFileList(AbstractFileType abstract_filetype, FileOperation fop);
+	void BuildFileList(AbstractFileType abstract_filetype, SaveLoadOperation fop);
 	const FiosItem *FindItem(const char *file);
 
 	SmallVector<FiosItem, 32> files; ///< The list of files.
@@ -207,11 +207,11 @@ DECLARE_ENUM_AS_BIT_SET(SortingBits)
 /* Variables to display file lists */
 extern SortingBits _savegame_sort_order;
 
-void ShowSaveLoadDialog(AbstractFileType abstract_filetype, FileOperation fop);
+void ShowSaveLoadDialog(AbstractFileType abstract_filetype, SaveLoadOperation fop);
 
-void FiosGetSavegameList(FileOperation fop, FileList &file_list);
-void FiosGetScenarioList(FileOperation fop, FileList &file_list);
-void FiosGetHeightmapList(FileOperation fop, FileList &file_list);
+void FiosGetSavegameList(SaveLoadOperation fop, FileList &file_list);
+void FiosGetScenarioList(SaveLoadOperation fop, FileList &file_list);
+void FiosGetHeightmapList(SaveLoadOperation fop, FileList &file_list);
 
 const char *FiosBrowseTo(const FiosItem *item);
 
@@ -220,7 +220,7 @@ bool FiosDelete(const char *name);
 void FiosMakeHeightmapName(char *buf, const char *name, const char *last);
 void FiosMakeSavegameName(char *buf, const char *name, const char *last);
 
-FiosType FiosGetSavegameListCallback(FileOperation fop, const char *file, const char *ext, char *title, const char *last);
+FiosType FiosGetSavegameListCallback(SaveLoadOperation fop, const char *file, const char *ext, char *title, const char *last);
 
 int CDECL CompareFiosItems(const FiosItem *a, const FiosItem *b);
 
diff --git a/src/fios_gui.cpp b/src/fios_gui.cpp
index a0f0f1b296..e6cd9625cc 100644
--- a/src/fios_gui.cpp
+++ b/src/fios_gui.cpp
@@ -229,7 +229,7 @@ struct SaveLoadWindow : public Window {
 private:
 	QueryString filename_editbox; ///< Filename editbox.
 	AbstractFileType abstract_filetype; /// Type of file to select.
-	FileOperation fop;            ///< File operation to perform.
+	SaveLoadOperation fop;        ///< File operation to perform.
 	FileList fios_items;          ///< Save game list.
 	FiosItem o_dir;
 	const FiosItem *selected;     ///< Selected game in #fios_items, or \c NULL.
@@ -243,13 +243,13 @@ public:
 		this->filename_editbox.text.UpdateSize();
 	}
 
-	SaveLoadWindow(WindowDesc *desc, AbstractFileType abstract_filetype, FileOperation fop)
+	SaveLoadWindow(WindowDesc *desc, AbstractFileType abstract_filetype, SaveLoadOperation fop)
 			: Window(desc), filename_editbox(64), abstract_filetype(abstract_filetype), fop(fop)
 	{
-		assert(this->fop == FOP_SAVE || this->fop == FOP_LOAD);
+		assert(this->fop == SLO_SAVE || this->fop == SLO_LOAD);
 
 		/* For saving, construct an initial file name. */
-		if (this->fop == FOP_SAVE) {
+		if (this->fop == SLO_SAVE) {
 			switch (this->abstract_filetype) {
 				case FT_SAVEGAME:
 					this->GenerateFileName();
@@ -268,7 +268,7 @@ public:
 		this->filename_editbox.ok_button = WID_SL_SAVE_GAME;
 
 		this->CreateNestedTree(true);
-		if (this->fop == FOP_LOAD && this->abstract_filetype == FT_SAVEGAME) {
+		if (this->fop == SLO_LOAD && this->abstract_filetype == FT_SAVEGAME) {
 			this->GetWidget<NWidgetStacked>(WID_SL_CONTENT_DOWNLOAD_SEL)->SetDisplayedPlane(SZSP_HORIZONTAL);
 		}
 
@@ -276,15 +276,15 @@ public:
 		StringID caption_string;
 		switch (this->abstract_filetype) {
 			case FT_SAVEGAME:
-				caption_string = (this->fop == FOP_SAVE) ? STR_SAVELOAD_SAVE_CAPTION : STR_SAVELOAD_LOAD_CAPTION;
+				caption_string = (this->fop == SLO_SAVE) ? STR_SAVELOAD_SAVE_CAPTION : STR_SAVELOAD_LOAD_CAPTION;
 				break;
 
 			case FT_SCENARIO:
-				caption_string = (this->fop == FOP_SAVE) ? STR_SAVELOAD_SAVE_SCENARIO : STR_SAVELOAD_LOAD_SCENARIO;
+				caption_string = (this->fop == SLO_SAVE) ? STR_SAVELOAD_SAVE_SCENARIO : STR_SAVELOAD_LOAD_SCENARIO;
 				break;
 
 			case FT_HEIGHTMAP:
-				caption_string = (this->fop == FOP_SAVE) ? STR_SAVELOAD_SAVE_HEIGHTMAP : STR_SAVELOAD_LOAD_HEIGHTMAP;
+				caption_string = (this->fop == SLO_SAVE) ? STR_SAVELOAD_SAVE_HEIGHTMAP : STR_SAVELOAD_LOAD_HEIGHTMAP;
 				break;
 
 			default:
@@ -328,7 +328,7 @@ public:
 		}
 
 		/* Focus the edit box by default in the save windows */
-		if (this->fop == FOP_SAVE) this->SetFocusedWidget(WID_SL_SAVE_OSK_TITLE);
+		if (this->fop == SLO_SAVE) this->SetFocusedWidget(WID_SL_SAVE_OSK_TITLE);
 	}
 
 	virtual ~SaveLoadWindow()
@@ -438,7 +438,7 @@ public:
 					}
 
 					/* Hide the NewGRF stuff when saving. We also hide the button. */
-					if (this->fop == FOP_LOAD && (this->abstract_filetype == FT_SAVEGAME || this->abstract_filetype == FT_SCENARIO)) {
+					if (this->fop == SLO_LOAD && (this->abstract_filetype == FT_SAVEGAME || this->abstract_filetype == FT_SCENARIO)) {
 						y += WD_PAR_VSEP_NORMAL;
 						if (y > y_max) break;
 
@@ -583,19 +583,19 @@ public:
 
 							if (GetDetailedFileType(file->type) == DFT_GAME_FILE) {
 								/* Other detailed file types cannot be checked before. */
-								SaveOrLoad(name, FOP_CHECK, DFT_GAME_FILE, NO_DIRECTORY, false);
+								SaveOrLoad(name, SLO_CHECK, DFT_GAME_FILE, NO_DIRECTORY, false);
 							}
 
 							this->InvalidateData(1);
 						}
-						if (this->fop == FOP_SAVE) {
+						if (this->fop == SLO_SAVE) {
 							/* Copy clicked name to editbox */
 							this->filename_editbox.text.Assign(file->title);
 							this->SetWidgetDirty(WID_SL_SAVE_OSK_TITLE);
 						}
 					} else if (!_load_check_data.HasErrors()) {
 						this->selected = file;
-						if (this->fop == FOP_LOAD) {
+						if (this->fop == SLO_LOAD) {
 							if (this->abstract_filetype == FT_SAVEGAME || this->abstract_filetype == FT_SCENARIO) {
 								this->OnClick(pt, WID_SL_LOAD_BUTTON, 1);
 							} else {
@@ -621,7 +621,7 @@ public:
 					ShowErrorMessage(STR_NETWORK_ERROR_NOTAVAILABLE, INVALID_STRING_ID, WL_ERROR);
 				} else {
 #if defined(ENABLE_NETWORK)
-					assert(this->fop == FOP_LOAD);
+					assert(this->fop == SLO_LOAD);
 					switch (this->abstract_filetype) {
 						default: NOT_REACHED();
 						case FT_SCENARIO:  ShowNetworkContentListWindow(NULL, CONTENT_TYPE_SCENARIO);  break;
@@ -654,7 +654,7 @@ public:
 	virtual void OnTimeout()
 	{
 		/* Widgets WID_SL_DELETE_SELECTION and WID_SL_SAVE_GAME only exist when saving to a file. */
-		if (this->fop != FOP_SAVE) return;
+		if (this->fop != SLO_SAVE) return;
 
 		if (this->IsWidgetLowered(WID_SL_DELETE_SELECTION)) { // Delete button clicked
 			if (!FiosDelete(this->filename_editbox.text.buf)) {
@@ -707,7 +707,7 @@ public:
 				/* Selection changes */
 				if (!gui_scope) break;
 
-				if (this->fop != FOP_LOAD) break;
+				if (this->fop != SLO_LOAD) break;
 
 				switch (this->abstract_filetype) {
 					case FT_HEIGHTMAP:
@@ -764,12 +764,12 @@ static WindowDesc _save_dialog_desc(
  * @param abstract_filetype Kind of file to handle.
  * @param fop File operation to perform (load or save).
  */
-void ShowSaveLoadDialog(AbstractFileType abstract_filetype, FileOperation fop)
+void ShowSaveLoadDialog(AbstractFileType abstract_filetype, SaveLoadOperation fop)
 {
 	DeleteWindowById(WC_SAVELOAD, 0);
 
 	WindowDesc *sld;
-	if (fop == FOP_SAVE) {
+	if (fop == SLO_SAVE) {
 		sld = &_save_dialog_desc;
 	} else {
 		/* Dialogue for loading a file. */
diff --git a/src/genworld.cpp b/src/genworld.cpp
index 95e28fcdf0..a08b323116 100644
--- a/src/genworld.cpp
+++ b/src/genworld.cpp
@@ -204,7 +204,7 @@ static void _GenerateWorld(void *)
 		if (_debug_desync_level > 0) {
 			char name[MAX_PATH];
 			seprintf(name, lastof(name), "dmp_cmds_%08x_%08x.sav", _settings_game.game_creation.generation_seed, _date);
-			SaveOrLoad(name, FOP_SAVE, DFT_GAME_FILE, AUTOSAVE_DIR, false);
+			SaveOrLoad(name, SLO_SAVE, DFT_GAME_FILE, AUTOSAVE_DIR, false);
 		}
 	} catch (...) {
 		BasePersistentStorageArray::SwitchMode(PSM_LEAVE_GAMELOOP, true);
diff --git a/src/intro_gui.cpp b/src/intro_gui.cpp
index b6ac73cb74..a09a59a10d 100644
--- a/src/intro_gui.cpp
+++ b/src/intro_gui.cpp
@@ -111,9 +111,9 @@ struct SelectGameWindow : public Window {
 				}
 				break;
 
-			case WID_SGI_LOAD_GAME:      ShowSaveLoadDialog(FT_SAVEGAME, FOP_LOAD); break;
-			case WID_SGI_PLAY_SCENARIO:  ShowSaveLoadDialog(FT_SCENARIO, FOP_LOAD); break;
-			case WID_SGI_PLAY_HEIGHTMAP: ShowSaveLoadDialog(FT_HEIGHTMAP,FOP_LOAD); break;
+			case WID_SGI_LOAD_GAME:      ShowSaveLoadDialog(FT_SAVEGAME, SLO_LOAD); break;
+			case WID_SGI_PLAY_SCENARIO:  ShowSaveLoadDialog(FT_SCENARIO, SLO_LOAD); break;
+			case WID_SGI_PLAY_HEIGHTMAP: ShowSaveLoadDialog(FT_HEIGHTMAP,SLO_LOAD); break;
 			case WID_SGI_EDIT_SCENARIO:  StartScenarioEditor(); break;
 
 			case WID_SGI_PLAY_NETWORK:
diff --git a/src/network/network_client.cpp b/src/network/network_client.cpp
index a33e5c6814..edfe4587f3 100644
--- a/src/network/network_client.cpp
+++ b/src/network/network_client.cpp
@@ -520,7 +520,7 @@ bool ClientNetworkGameSocketHandler::IsConnected()
  *   DEF_CLIENT_RECEIVE_COMMAND has parameter: Packet *p
  ************/
 
-extern bool SafeLoad(const char *filename, FileOperation fop, DetailedFileType dft, GameMode newgm, Subdirectory subdir, struct LoadFilter *lf = NULL);
+extern bool SafeLoad(const char *filename, SaveLoadOperation fop, DetailedFileType dft, GameMode newgm, Subdirectory subdir, struct LoadFilter *lf = NULL);
 
 NetworkRecvStatus ClientNetworkGameSocketHandler::Receive_SERVER_FULL(Packet *p)
 {
@@ -836,7 +836,7 @@ NetworkRecvStatus ClientNetworkGameSocketHandler::Receive_SERVER_MAP_DONE(Packet
 
 	/* The map is done downloading, load it */
 	ClearErrorMessages();
-	bool load_success = SafeLoad(NULL, FOP_LOAD, DFT_GAME_FILE, GM_NORMAL, NO_DIRECTORY, lf);
+	bool load_success = SafeLoad(NULL, SLO_LOAD, DFT_GAME_FILE, GM_NORMAL, NO_DIRECTORY, lf);
 
 	/* Long savegame loads shouldn't affect the lag calculation! */
 	this->last_packet = _realtime_tick;
diff --git a/src/network/network_gui.cpp b/src/network/network_gui.cpp
index c3aef5b0fd..520c4f60a8 100644
--- a/src/network/network_gui.cpp
+++ b/src/network/network_gui.cpp
@@ -1187,17 +1187,17 @@ struct NetworkStartServerWindow : public Window {
 
 			case WID_NSS_LOAD_GAME:
 				_is_network_server = true;
-				ShowSaveLoadDialog(FT_SAVEGAME, FOP_LOAD);
+				ShowSaveLoadDialog(FT_SAVEGAME, SLO_LOAD);
 				break;
 
 			case WID_NSS_PLAY_SCENARIO:
 				_is_network_server = true;
-				ShowSaveLoadDialog(FT_SCENARIO, FOP_LOAD);
+				ShowSaveLoadDialog(FT_SCENARIO, SLO_LOAD);
 				break;
 
 			case WID_NSS_PLAY_HEIGHTMAP:
 				_is_network_server = true;
-				ShowSaveLoadDialog(FT_HEIGHTMAP,FOP_LOAD);
+				ShowSaveLoadDialog(FT_HEIGHTMAP,SLO_LOAD);
 				break;
 		}
 	}
diff --git a/src/openttd.cpp b/src/openttd.cpp
index f00ce74c37..58f011b082 100644
--- a/src/openttd.cpp
+++ b/src/openttd.cpp
@@ -328,7 +328,7 @@ static void LoadIntroGame(bool load_newgrfs = true)
 	SetupColoursAndInitialWindow();
 
 	/* Load the default opening screen savegame */
-	if (SaveOrLoad("opntitle.dat", FOP_LOAD, DFT_GAME_FILE, BASESET_DIR) != SL_OK) {
+	if (SaveOrLoad("opntitle.dat", SLO_LOAD, DFT_GAME_FILE, BASESET_DIR) != SL_OK) {
 		GenerateWorld(GWM_EMPTY, 64, 64); // if failed loading, make empty world.
 		WaitTillGeneratedWorld();
 		SetLocalCompany(COMPANY_SPECTATOR);
@@ -621,12 +621,12 @@ int openttd_main(int argc, char *argv[])
 				_file_to_saveload.SetName(mgo.opt);
 				bool is_scenario = _switch_mode == SM_EDITOR || _switch_mode == SM_LOAD_SCENARIO;
 				_switch_mode = is_scenario ? SM_LOAD_SCENARIO : SM_LOAD_GAME;
-				_file_to_saveload.SetMode(FOP_LOAD, is_scenario ? FT_SCENARIO : FT_SAVEGAME, DFT_GAME_FILE);
+				_file_to_saveload.SetMode(SLO_LOAD, is_scenario ? FT_SCENARIO : FT_SAVEGAME, DFT_GAME_FILE);
 
 				/* if the file doesn't exist or it is not a valid savegame, let the saveload code show an error */
 				const char *t = strrchr(_file_to_saveload.name, '.');
 				if (t != NULL) {
-					FiosType ft = FiosGetSavegameListCallback(FOP_LOAD, _file_to_saveload.name, t, NULL, NULL);
+					FiosType ft = FiosGetSavegameListCallback(SLO_LOAD, _file_to_saveload.name, t, NULL, NULL);
 					if (ft != FIOS_TYPE_INVALID) _file_to_saveload.SetMode(ft);
 				}
 
@@ -648,10 +648,10 @@ int openttd_main(int argc, char *argv[])
 
 			char title[80];
 			title[0] = '\0';
-			FiosGetSavegameListCallback(FOP_LOAD, mgo.opt, strrchr(mgo.opt, '.'), title, lastof(title));
+			FiosGetSavegameListCallback(SLO_LOAD, mgo.opt, strrchr(mgo.opt, '.'), title, lastof(title));
 
 			_load_check_data.Clear();
-			SaveOrLoadResult res = SaveOrLoad(mgo.opt, FOP_CHECK, DFT_GAME_FILE, SAVE_DIR, false);
+			SaveOrLoadResult res = SaveOrLoad(mgo.opt, SLO_CHECK, DFT_GAME_FILE, SAVE_DIR, false);
 			if (res != SL_OK || _load_check_data.HasErrors()) {
 				fprintf(stderr, "Failed to open savegame\n");
 				if (_load_check_data.HasErrors()) {
@@ -998,9 +998,9 @@ static void MakeNewEditorWorld()
  * @param subdir default directory to look for filename, set to 0 if not needed
  * @param lf Load filter to use, if NULL: use filename + subdir.
  */
-bool SafeLoad(const char *filename, FileOperation fop, DetailedFileType dft, GameMode newgm, Subdirectory subdir, struct LoadFilter *lf = NULL)
+bool SafeLoad(const char *filename, SaveLoadOperation fop, DetailedFileType dft, GameMode newgm, Subdirectory subdir, struct LoadFilter *lf = NULL)
 {
-	assert(fop == FOP_LOAD);
+	assert(fop == SLO_LOAD);
 	assert(dft == DFT_GAME_FILE || (lf == NULL && dft == DFT_OLD_GAME_FILE));
 	GameMode ogm = _game_mode;
 
@@ -1158,7 +1158,7 @@ void SwitchToMode(SwitchMode new_mode)
 
 		case SM_SAVE_GAME: // Save game.
 			/* Make network saved games on pause compatible to singleplayer */
-			if (SaveOrLoad(_file_to_saveload.name, FOP_SAVE, DFT_GAME_FILE, NO_DIRECTORY) != SL_OK) {
+			if (SaveOrLoad(_file_to_saveload.name, SLO_SAVE, DFT_GAME_FILE, NO_DIRECTORY) != SL_OK) {
 				SetDParamStr(0, GetSaveLoadErrorString());
 				ShowErrorMessage(STR_JUST_RAW_STRING, INVALID_STRING_ID, WL_ERROR);
 			} else {
@@ -1369,7 +1369,7 @@ void StateGameLoop()
 			/* Save the desync savegame if needed. */
 			char name[MAX_PATH];
 			seprintf(name, lastof(name), "dmp_cmds_%08x_%08x.sav", _settings_game.game_creation.generation_seed, _date);
-			SaveOrLoad(name, FOP_SAVE, DFT_GAME_FILE, AUTOSAVE_DIR, false);
+			SaveOrLoad(name, SLO_SAVE, DFT_GAME_FILE, AUTOSAVE_DIR, false);
 		}
 
 		CheckCaches();
@@ -1426,7 +1426,7 @@ static void DoAutosave()
 	}
 
 	DEBUG(sl, 2, "Autosaving to '%s'", buf);
-	if (SaveOrLoad(buf, FOP_SAVE, DFT_GAME_FILE, AUTOSAVE_DIR) != SL_OK) {
+	if (SaveOrLoad(buf, SLO_SAVE, DFT_GAME_FILE, AUTOSAVE_DIR) != SL_OK) {
 		ShowErrorMessage(STR_ERROR_AUTOSAVE_FAILED, INVALID_STRING_ID, WL_ERROR);
 	}
 }
diff --git a/src/saveload/saveload.cpp b/src/saveload/saveload.cpp
index 8da0d03984..7b7341115a 100644
--- a/src/saveload/saveload.cpp
+++ b/src/saveload/saveload.cpp
@@ -2778,10 +2778,10 @@ SaveOrLoadResult LoadWithFilter(LoadFilter *reader)
  * @param threaded True when threaded saving is allowed
  * @return Return the result of the action. #SL_OK, #SL_ERROR, or #SL_REINIT ("unload" the game)
  */
-SaveOrLoadResult SaveOrLoad(const char *filename, FileOperation fop, DetailedFileType dft, Subdirectory sb, bool threaded)
+SaveOrLoadResult SaveOrLoad(const char *filename, SaveLoadOperation fop, DetailedFileType dft, Subdirectory sb, bool threaded)
 {
 	/* An instance of saving is already active, so don't go saving again */
-	if (_sl.saveinprogress && fop == FOP_SAVE && dft == DFT_GAME_FILE && threaded) {
+	if (_sl.saveinprogress && fop == SLO_SAVE && dft == DFT_GAME_FILE && threaded) {
 		/* if not an autosave, but a user action, show error message */
 		if (!_do_autosave) ShowErrorMessage(STR_ERROR_SAVE_STILL_IN_PROGRESS, INVALID_STRING_ID, WL_ERROR);
 		return SL_OK;
@@ -2790,7 +2790,7 @@ SaveOrLoadResult SaveOrLoad(const char *filename, FileOperation fop, DetailedFil
 
 	try {
 		/* Load a TTDLX or TTDPatch game */
-		if (fop == FOP_LOAD && dft == DFT_OLD_GAME_FILE) {
+		if (fop == SLO_LOAD && dft == DFT_OLD_GAME_FILE) {
 			InitializeGame(256, 256, true, true); // set a mapsize of 256x256 for TTDPatch games or it might get confused
 
 			/* TTD/TTO savegames have no NewGRFs, TTDP savegame have them
@@ -2813,33 +2813,33 @@ SaveOrLoadResult SaveOrLoad(const char *filename, FileOperation fop, DetailedFil
 
 		assert(dft == DFT_GAME_FILE);
 		switch (fop) {
-			case FOP_CHECK:
+			case SLO_CHECK:
 				_sl.action = SLA_LOAD_CHECK;
 				break;
 
-			case FOP_LOAD:
+			case SLO_LOAD:
 				_sl.action = SLA_LOAD;
 				break;
 
-			case FOP_SAVE:
+			case SLO_SAVE:
 				_sl.action = SLA_SAVE;
 				break;
 
 			default: NOT_REACHED();
 		}
 
-		FILE *fh = (fop == FOP_SAVE) ? FioFOpenFile(filename, "wb", sb) : FioFOpenFile(filename, "rb", sb);
+		FILE *fh = (fop == SLO_SAVE) ? FioFOpenFile(filename, "wb", sb) : FioFOpenFile(filename, "rb", sb);
 
 		/* Make it a little easier to load savegames from the console */
-		if (fh == NULL && fop != FOP_SAVE) fh = FioFOpenFile(filename, "rb", SAVE_DIR);
-		if (fh == NULL && fop != FOP_SAVE) fh = FioFOpenFile(filename, "rb", BASE_DIR);
-		if (fh == NULL && fop != FOP_SAVE) fh = FioFOpenFile(filename, "rb", SCENARIO_DIR);
+		if (fh == NULL && fop != SLO_SAVE) fh = FioFOpenFile(filename, "rb", SAVE_DIR);
+		if (fh == NULL && fop != SLO_SAVE) fh = FioFOpenFile(filename, "rb", BASE_DIR);
+		if (fh == NULL && fop != SLO_SAVE) fh = FioFOpenFile(filename, "rb", SCENARIO_DIR);
 
 		if (fh == NULL) {
-			SlError(fop == FOP_SAVE ? STR_GAME_SAVELOAD_ERROR_FILE_NOT_WRITEABLE : STR_GAME_SAVELOAD_ERROR_FILE_NOT_READABLE);
+			SlError(fop == SLO_SAVE ? STR_GAME_SAVELOAD_ERROR_FILE_NOT_WRITEABLE : STR_GAME_SAVELOAD_ERROR_FILE_NOT_READABLE);
 		}
 
-		if (fop == FOP_SAVE) { // SAVE game
+		if (fop == SLO_SAVE) { // SAVE game
 			DEBUG(desync, 1, "save: %08x; %02x; %s", _date, _date_fract, filename);
 			if (_network_server || !_settings_client.gui.threaded_saves) threaded = false;
 
@@ -2847,25 +2847,25 @@ SaveOrLoadResult SaveOrLoad(const char *filename, FileOperation fop, DetailedFil
 		}
 
 		/* LOAD game */
-		assert(fop == FOP_LOAD || fop == FOP_CHECK);
+		assert(fop == SLO_LOAD || fop == SLO_CHECK);
 		DEBUG(desync, 1, "load: %s", filename);
-		return DoLoad(new FileReader(fh), fop == FOP_CHECK);
+		return DoLoad(new FileReader(fh), fop == SLO_CHECK);
 	} catch (...) {
 		/* This code may be executed both for old and new save games. */
 		ClearSaveLoadState();
 
 		/* Skip the "colour" character */
-		if (fop != FOP_CHECK) DEBUG(sl, 0, "%s", GetSaveLoadErrorString() + 3);
+		if (fop != SLO_CHECK) DEBUG(sl, 0, "%s", GetSaveLoadErrorString() + 3);
 
 		/* A saver/loader exception!! reinitialize all variables to prevent crash! */
-		return (fop == FOP_LOAD) ? SL_REINIT : SL_ERROR;
+		return (fop == SLO_LOAD) ? SL_REINIT : SL_ERROR;
 	}
 }
 
 /** Do a save when exiting the game (_settings_client.gui.autosave_on_exit) */
 void DoExitSave()
 {
-	SaveOrLoad("exit.sav", FOP_SAVE, DFT_GAME_FILE, AUTOSAVE_DIR);
+	SaveOrLoad("exit.sav", SLO_SAVE, DFT_GAME_FILE, AUTOSAVE_DIR);
 }
 
 /**
@@ -2909,7 +2909,7 @@ void GenerateDefaultSaveName(char *buf, const char *last)
  */
 void FileToSaveLoad::SetMode(FiosType ft)
 {
-	this->SetMode(FOP_LOAD, GetAbstractFileType(ft), GetDetailedFileType(ft));
+	this->SetMode(SLO_LOAD, GetAbstractFileType(ft), GetDetailedFileType(ft));
 }
 
 /**
@@ -2918,10 +2918,10 @@ void FileToSaveLoad::SetMode(FiosType ft)
  * @param aft Abstract file type.
  * @param dft Detailed file type.
  */
-void FileToSaveLoad::SetMode(FileOperation fop, AbstractFileType aft, DetailedFileType dft)
+void FileToSaveLoad::SetMode(SaveLoadOperation fop, AbstractFileType aft, DetailedFileType dft)
 {
 	if (aft == FT_INVALID || aft == FT_NONE) {
-		this->file_op = FOP_INVALID;
+		this->file_op = SLO_INVALID;
 		this->detail_ftype = DFT_INVALID;
 		this->abstract_ftype = FT_INVALID;
 		return;
diff --git a/src/saveload/saveload.h b/src/saveload/saveload.h
index b25e91e2cd..1513355c8d 100644
--- a/src/saveload/saveload.h
+++ b/src/saveload/saveload.h
@@ -24,14 +24,14 @@ enum SaveOrLoadResult {
 
 /** Deals with the type of the savegame, independent of extension */
 struct FileToSaveLoad {
-	FileOperation file_op;           ///< File operation to perform.
+	SaveLoadOperation file_op;           ///< File operation to perform.
 	DetailedFileType detail_ftype;   ///< Concrete file type (PNG, BMP, old save, etc).
 	AbstractFileType abstract_ftype; ///< Abstract type of file (scenario, heightmap, etc).
 	char name[MAX_PATH];             ///< Name of the file.
 	char title[255];                 ///< Internal name of the game.
 
 	void SetMode(FiosType ft);
-	void SetMode(FileOperation fop, AbstractFileType aft, DetailedFileType dft);
+	void SetMode(SaveLoadOperation fop, AbstractFileType aft, DetailedFileType dft);
 	void SetName(const char *name);
 	void SetTitle(const char *title);
 };
@@ -51,7 +51,7 @@ extern FileToSaveLoad _file_to_saveload;
 void GenerateDefaultSaveName(char *buf, const char *last);
 void SetSaveLoadError(uint16 str);
 const char *GetSaveLoadErrorString();
-SaveOrLoadResult SaveOrLoad(const char *filename, FileOperation fop, DetailedFileType dft, Subdirectory sb, bool threaded = true);
+SaveOrLoadResult SaveOrLoad(const char *filename, SaveLoadOperation fop, DetailedFileType dft, Subdirectory sb, bool threaded = true);
 void WaitTillSaved();
 void ProcessAsyncSaveFinish();
 void DoExitSave();
diff --git a/src/toolbar_gui.cpp b/src/toolbar_gui.cpp
index 55b49fd748..2649552f45 100644
--- a/src/toolbar_gui.cpp
+++ b/src/toolbar_gui.cpp
@@ -427,17 +427,17 @@ static CallBackFunction MenuClickSaveLoad(int index = 0)
 {
 	if (_game_mode == GM_EDITOR) {
 		switch (index) {
-			case SLEME_SAVE_SCENARIO:  ShowSaveLoadDialog(FT_SCENARIO, FOP_SAVE);  break;
-			case SLEME_LOAD_SCENARIO:  ShowSaveLoadDialog(FT_SCENARIO, FOP_LOAD);  break;
-			case SLEME_SAVE_HEIGHTMAP: ShowSaveLoadDialog(FT_HEIGHTMAP,FOP_SAVE); break;
-			case SLEME_LOAD_HEIGHTMAP: ShowSaveLoadDialog(FT_HEIGHTMAP,FOP_LOAD); break;
+			case SLEME_SAVE_SCENARIO:  ShowSaveLoadDialog(FT_SCENARIO, SLO_SAVE);  break;
+			case SLEME_LOAD_SCENARIO:  ShowSaveLoadDialog(FT_SCENARIO, SLO_LOAD);  break;
+			case SLEME_SAVE_HEIGHTMAP: ShowSaveLoadDialog(FT_HEIGHTMAP,SLO_SAVE); break;
+			case SLEME_LOAD_HEIGHTMAP: ShowSaveLoadDialog(FT_HEIGHTMAP,SLO_LOAD); break;
 			case SLEME_EXIT_TOINTRO:   AskExitToGameMenu();                    break;
 			case SLEME_EXIT_GAME:      HandleExitGameRequest();                break;
 		}
 	} else {
 		switch (index) {
-			case SLNME_SAVE_GAME:      ShowSaveLoadDialog(FT_SAVEGAME, FOP_SAVE); break;
-			case SLNME_LOAD_GAME:      ShowSaveLoadDialog(FT_SAVEGAME, FOP_LOAD); break;
+			case SLNME_SAVE_GAME:      ShowSaveLoadDialog(FT_SAVEGAME, SLO_SAVE); break;
+			case SLNME_LOAD_GAME:      ShowSaveLoadDialog(FT_SAVEGAME, SLO_LOAD); break;
 			case SLNME_EXIT_TOINTRO:   AskExitToGameMenu();               break;
 			case SLNME_EXIT_GAME:      HandleExitGameRequest();           break;
 		}
@@ -1712,7 +1712,7 @@ struct MainToolbarWindow : Window {
 			case MTHK_FASTFORWARD: ToolbarFastForwardClick(this); break;
 			case MTHK_SETTINGS: ShowGameOptions(); break;
 			case MTHK_SAVEGAME: MenuClickSaveLoad(); break;
-			case MTHK_LOADGAME: ShowSaveLoadDialog(FT_SAVEGAME, FOP_LOAD); break;
+			case MTHK_LOADGAME: ShowSaveLoadDialog(FT_SAVEGAME, SLO_LOAD); break;
 			case MTHK_SMALLMAP: ShowSmallMap(); break;
 			case MTHK_TOWNDIRECTORY: ShowTownDirectory(); break;
 			case MTHK_SUBSIDIES: ShowSubsidiesList(); break;
diff --git a/src/video/dedicated_v.cpp b/src/video/dedicated_v.cpp
index 95d40cd000..e038df9751 100644
--- a/src/video/dedicated_v.cpp
+++ b/src/video/dedicated_v.cpp
@@ -142,7 +142,7 @@ static void *_dedicated_video_mem;
 /* Whether a fork has been done. */
 bool _dedicated_forks;
 
-extern bool SafeLoad(const char *filename, FileOperation fop, DetailedFileType dft, GameMode newgm, Subdirectory subdir, struct LoadFilter *lf = NULL);
+extern bool SafeLoad(const char *filename, SaveLoadOperation fop, DetailedFileType dft, GameMode newgm, Subdirectory subdir, struct LoadFilter *lf = NULL);
 
 static FVideoDriver_Dedicated iFVideoDriver_Dedicated;