N Viivi Play/Stop Button

The symbol 'N' refers to the component 'N' in the figure.

Clicking the Play/Stop Button in the initial/terminated-states changes the state to the next state.

Clicking it in the ready-state starts the evaluation continuously.

Clicking it in the halted-state restarts the evaluation continuously.

Clicking it in the evaluating-state proceeds the evaluation to an appropriate point, and then halts the evaluation.

In the above cases, clicking the Play/Stop-Button is equivalent to typing the Space-Bar on the keyboard.

Clicking it after typing a string in the input-line transfers the string to a corresponding input-port window and inputs it to Viivi kernel.
In this case, different from the case of the Enter-Button/Key, subsequent evaluations will proceeds continuously.