HEIDENHAIN TNC 426 PB/M Technical Manual page 552

6.13 Display and Operation
6 – 222
You can modify the display and operating modes of the TNC by editing the
machine parameters.
The display screen is divided into separate windows. The user can select the
operating functions through soft keys. (Also see the User's Manual)
HEIDENHAIN Technical Manual TNC 426, TNC 430