Sometimes it is desirable to terminate a function prematurely. To do this the user must first regain control over the command input to the tracking programs by entering the keyword KEYBOARD. This command will stop the processing of the function command string with the current command. However, if the currently active command is a data collection command, then it will continue to run in the usual way until completion. If the user wishes to terminate the program as well, it is necessary to use the STOP command to abort the program.