Protection and backup

The backup

When a billboard starts, the engine saves the original blocks of the whole wall in the world save (data/billboard/wall_backups.dat). A crash or a server restart does not lose them.

The wall comes back:

• when you press Restore,
• when you break the engine,
• after runOff() or /billboard runoff, once the text has left the wall.

Stop does not restore: the text stays where it is.

The frozen wall

While a billboard is shown (running or stopped), no block of its wall can be replaced:

• players can't mine it, also not in creative mode (This block belongs to an active billboard. Press Restore on its engine first.),
• explosions (TNT, creepers) leave it standing,
• pistons can't push or pull it,
• mobs can't change it (endermen, withers),
• /setblock and /fill can't change it.

That is why the pixel block is free: nobody can mine a gold-block text and keep the gold.

Blocks in the wall may still change their own state, for example a redstone lamp lighting up. Blocks attached to the wall from outside (levers, torches, vines, buttons) stay put.

Unloaded chunks

Scrolling pauses while the wall's chunks are not loaded and goes on when you come back. A billboard far away from all players therefore does not use any server time.