# Outputs

Outputs are the symbols you write on the right-hand-side of a rule diagram to say what to do when a rule has been matched.\
In the SandPond engine, some are built-in already:

* `@` Place this atom in the space.
* `_` Empty the space.
* `.` Do nothing.

You can [make your own output symbols](symbols) with the following keywords:

* `symbol`
* `change`
* `keep`
