The at commands you entered before are still active in the server. You need a way to stop them if you want to do something else. The tagging mechanism will enable you to do that.

A tag in a name associated to a command. To tag a command with the name mytag, simply prefix the command. For example :

  mytag: at (decibel.val > 0.7) wheels.speed = 0;

will launch the event catching command using the decibel sensor with tag mytag.

Later you will be able to stop that command :

  stop mytag;

will stop the previous command and the robot will not react to sound anymore.

The default tag when you don't specify one is notag. Therefore :

  stop notag;

will stop all the commands you type since the beginning of this tutorial.

It if also possible to freeze temporarily a command :

  freeze mytag;

will stop the commands tagged with mytag, but it will not be deleted, and

  unfreeze mytag;

will resume the command.