IBM 6400 Setup Manual page 124

These keys are summarized in a legend box at the lower right corner of each
configuration menu diagram.
4–8 6400 Line Matrix Printers Setup Guide, Cabinet and Pedestal Models
The Return key moves you back up the menu structure.
The Scroll key moves forward through the options at a particular
menu level.
The Scroll± key moves backward through the options at a particular
menu level.