# Layer Config

- Projection
- Position
- History

### undo, save

Set the maximum number of past configurations that can be saved in memory, using the undo and save mechanisms. Everytime this number is exceeded, the oldest configuration is discarded forever.

Although the number of undo and save levels does not affect performance, the memory required to handle multiple windows, with multiple layers, each layer with undo and save past configurations in memory, can be significant. Therefore, undo and save parameters should be kept to relatively low values, particularly undo, where new configurations are generated automatically, without any user intervention. save works exactly as undo, except that configurations are saved manually by users.

    Example: <layer undo="5" save="5"/> (default)
    (defined in GAMGI_ENGINE_UNDO and  GAMGI_ENGINE_SAVE)
    Allowed values: non-negative integer (optional)

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