When using the Pterm emulator, you will be asked to use several keys that existed on the PLATO keyboard, but no longer exist for modern keyboards. The following key combinations are how you now use these extinct comands:

NEXT = Enter HELP = F6 LAB = F7 BACK = F8 DATA = F9 STOP = F10

There are more PLATO commands, but the ones above are the only ones you will encounter in The Dungeon. A full list of PLATO key commands can be found on the Cyber1 website: https://www.cyber1.org/keyboard.asp