The keyboard uses one button for each finger and two for the thumb of the user's right hand. The five buttons immediately beneath the fingers are pressed in different combinations to generate all letters. The second thumb button is used to toggle through a range of modes that allow the user to switch case, enter numbers, insert punctuation and even add ASCII control characters, to be used in editing the document being prepared. To type a letter "T", for example, the user would tap the top thumb button to shift to uppercase, then chord a "t" by pressing the index finger and ring finger buttons simultaneously.