Apple Power Macintosh 5260 Series - Manual (Page 10)

Connecting a keyboard with a separate cable
1 Plug the mouse cable into the port on either side of the keyboard.
Most right-handed people prefer to use the mouse with their right hand; most
left-handed people prefer to use their left hand. Plug the mouse into the port
on the side you prefer.
The plug and the port are marked with the ◊ icon (symbol). Align the icons
before you insert the plug. (The positions of the port and icon on your
keyboard may be different from those pictured here.)
By the way: A port marked with the ◊ icon is called an Apple Desktop Bus
(ADB) port.
ADB icon
8 Chapter 1