# Reserved Names

Ren'Py reserves all names beginning with a single underscore (_). Do not use names beginning with an underscore, as that may cause your game to break in future versions of Ren'Py.

The following is a list of names that are used by Python. Re-using these names can lead to obscure problems.

- ArithmeticError
- AssertionError
- AttributeError
- BaseException
- BufferError
- BytesWarning
- DeprecationWarning
- EOFError
- Ellipsis
- EnvironmentError
- Exception
- False
- FloatingPointError
- FutureWarning
- GeneratorExit
- IOError
- ImportError
- ImportWarning
- IndentationError
- IndexError
- KeyError
- KeyboardInterrupt
- LookupError
- MemoryError
- NameError
- None
- NoneType
- NotImplemented
- NotImplementedError
- OSError
- OverflowError
- PPP
- PendingDeprecationWarning
- ReferenceError
- RuntimeError
- RuntimeWarning
- StandardError
- StopIteration
- SyntaxError
- SyntaxWarning
- SystemError
- SystemExit
- TabError
- True
- TypeError
- UnboundLocalError
- UnicodeDecodeError
- UnicodeEncodeError
- UnicodeError
- UnicodeTranslateError
- UnicodeWarning
- UserWarning
- ValueError
- Warning
- ZeroDivisionError
- abs
- all
- any
- apply
- basestring
- bin
- bool
- buffer
- bytearray
- bytes
- callable
- chr
- classmethod
- cmp
- coerce
- compile
- complex
- delattr
- dict
- dir
- divmod
- enumerate
- eval
- execfile
- file
- filter
- float
- format
- frozenset
- getattr
- globals
- hasattr
- hash
- hex
- id
- input
- int
- intern
- isinstance
- issubclass
- iter
- len
- list
- locals
- long
- map
- max
- memoryview
- min
- next
- object
- oct
- open
- ord
- pow
- print
- property
- range
- raw_input
- real_file
- reduce
- reload
- repr
- reversed
- round
- set
- setattr
- slice
- sorted
- staticmethod
- str
- sum
- super
- tuple
- type
- unichr
- unicode
- vars
- xrange
- zip

The following is a list of names that are used by Ren'Py. While in some cases it makes sense to redefine these names, one should be aware that doing so can cause obscure problems.

- ADVCharacter
- ADVSpeaker
- Action
- `AddToSet()`
- Alpha
- `AlphaBlend()`
- `AlphaDissolve()`
- `AlphaMask()`
- `AnimatedValue()`
- Animation
- `At()`
- `Attribute()`
- `AudioPositionValue()`
- Bar
- `BarValue`
- `Borders()`
- Button
- `Call()`
- `Character()`
- `Color`
- `ComposeTransition()`
- `Composite()`
- `Condition()`
- ConditionGroup
- `ConditionSwitch()`
- `Confirm()`
- `Crop()`
- `CropMove()`
- DictEquality
- `DictInputValue()`
- `DictValue()`
- `DisableAllInputValues()`
- `Dissolve()`
- `Drag`
- `DragGroup`
- DynamicCharacter
- `DynamicDisplayable()`
- `DynamicImage()`
- `EndReplay()`
- FactorZoom
- `Fade()`
- FieldEquality
- `FieldInputValue()`
- `FieldValue()`
- `FileAction()`
- `FileCurrentPage()`
- `FileCurrentScreenshot()`
- `FileDelete()`
- `FileJson()`
- `FileLoad()`
- `FileLoadable()`
- `FileNewest()`
- `FilePage()`
- `FilePageName()`
- `FilePageNameInputValue()`
- `FilePageNext()`
- `FilePagePrevious()`
- `FileSave()`
- `FileSaveName()`
- `FileScreenshot()`
- `FileSlotName()`
- `FileTakeScreenshot()`
- `FileTime()`
- `FileUsedSlots()`
- `Fixed()`
- `Flatten()`
- `FontGroup()`
- `Frame()`
- `Function()`
- `Gallery`
- `GamepadCalibrate()`
- `GamepadExists()`
- `GetTooltip()`
- `Grid()`
- `HBox()`
- `Help()`
- `Hide()`
- `HideInterface()`
- `If()`
- `Image()`
- ImageButton
- `ImageDissolve()`
- ImageReference
- Input
- `InputValue`
- `InvertSelected()`
- `Jump()`
- `Language()`
- `LayeredImage()`
- `LayeredImageProxy()`
- LiveComposite
- LiveCrop
- LiveTile
- `MainMenu()`
- `MixerValue()`
- Motion
- `MouseMove()`
- Move
- MoveFactory
- MoveIn
- MoveOut
- `MoveTransition()`
- `Movie()`
- `MultiPersistent`
- `MultipleTransition()`
- `MusicRoom`
- NVLCharacter
- NVLSpeaker
- `NoRollback`
- `Notify()`
- `Null()`
- `NullAction()`
- OldMoveTransition
- `OpenURL()`
- Pan
- `ParameterizedText()`
- Particles
- `Pause()`
- `PauseAudio()`
- `Pixellate()`
- `Placeholder()`
- Play
- `PlayCharacterVoice()`
- Position
- `Preference()`
- `PushMove()`
- `Queue()`
- `QueueEvent()`
- `QuickLoad()`
- `QuickSave()`
- `Quit()`
- `RemoveFromSet()`
- `Replay()`
- `RestartStatement()`
- `Return()`
- Revolve
- RevolveInOut
- `RollForward()`
- `Rollback()`
- `RollbackToIdentifier()`
- RotoZoom
- RoundRect
- `ScreenVariableInputValue()`
- `ScreenVariableValue()`
- `Screenshot()`
- `Scroll()`
- `SelectedIf()`
- `SensitiveIf()`
- Set
- `SetCharacterVolume()`
- `SetDict()`
- `SetField()`
- `SetMixer()`
- `SetMute()`
- `SetScreenVariable()`
- `SetVariable()`
- `SetVoiceMute()`
- `Show()`
- `ShowMenu()`
- `ShowTransient()`
- `ShowingSwitch()`
- `SideImage()`
- SizeZoom
- `Skip()`
- `SnowBlossom()`
- `Solid()`
- Speaker
- SplineMotion
- `Sprite`
- `SpriteManager`
- `Start()`
- `StaticValue()`
- Stop
- `Style`
- `StylePreference()`
- SubTransition
- `Text()`
- TextButton
- `Tile()`
- `ToggleDict()`
- `ToggleField()`
- `ToggleMute()`
- `ToggleScreen()`
- `ToggleScreenVariable()`
- `ToggleSetMembership()`
- `ToggleVariable()`
- `ToggleVoiceMute()`
- `Tooltip`
- `Transform`
- `VBox()`
- `VariableInputValue()`
- `VariableValue()`
- Viewport
- VoiceInfo
- `VoiceReplay()`
- Window
- `With()`
- `XScrollValue()`
- `YScrollValue()`
- Zoom
- ZoomInOut
- absolute
- achievement
- `adv`
- anim
- audio
- `blinds`
- build
- `center`
- centered
- color
- config
- default
- default_transition
- define
- director
- `dissolve`
- `ease`
- easeinbottom
- easeinleft
- easeinright
- easeintop
- easeoutbottom
- easeoutleft
- easeoutright
- easeouttop
- extend
- `fade`
- gui
- `hpunch`
- hyperlink_function
- hyperlink_sensitive
- hyperlink_styler
- i
- iap
- icon
- im
- `irisin`
- irisout
- layeredimage
- layout
- `left`
- library
- `main_menu`
- `menu`
- `mouse_visible`
- `move`
- moveinbottom
- moveinleft
- `moveinright`
- moveintop
- moveoutbottom
- moveoutleft
- `moveoutright`
- moveouttop
- `name_only`
- `narrator`
- nvl
- `nvl_clear()`
- nvl_clear_next
- nvl_erase
- `nvl_hide()`
- nvl_list
- `nvl_menu()`
- nvl_narrator
- `nvl_show()`
- nvl_show_core
- nvl_variant
- nvl_window
- `offscreenleft`
- `offscreenright`
- os
- persistent
- `pixellate`
- predict_menu
- predict_say
- preferences
- print_function
- pushdown
- pushleft
- `pushright`
- pushup
- python_dict
- python_list
- python_object
- python_set
- renpy
- `reset`
- `right`
- `save_name`
- `say`
- slideawaydown
- `slideawayleft`
- slideawayright
- slideawayup
- slidedown
- `slideleft`
- slideright
- slideup
- `squares`
- store
- style
- suppress_overlay
- `sv`
- sys
- theme
- toggle_skipping
- top
- `topleft`
- `topright`
- `truecenter`
- ui
- updater
- vcentered
- `voice()`
- `voice_can_replay()`
- `voice_replay()`
- `voice_sustain()`
- `vpunch`
- wipedown
- `wipeleft`
- wiperight
- wipeup
- `zoomin`
- `zoominout`
- `zoomout`

Ren'Py reserves filenames beginning with an underscore or "00".