IBM PCjr Manual page 25

These keys are called cursor control keys. In computer
talk, a cursor is a character (sometimes a blinking line
or block) that shows you where you are on the screen.
You can move a cursor up, down, right, or left with the
cursor control keys.
In this part of your "Keyboard Adventure," P.C. will
pretend to be a cursor to show you how to move around
the screen. Each of the cursor control keys moves P.C.
in the direction of the arrow. If a cursor control key is
pressed and released, P.C. will move one position and
stop. If the key is held down P.C. will continue to
move.
Getting Started 2-9