Epson Endeavor 468C - Manual (Page 29)

To connect the mouse to the built-in mouse port, plug the
connector into the port marked MOUSE, as shown below.
Caution
Although the connectors and ports for the mouse and
keyboard are physically identical, they cannot be used
interchangeably. Be sure to plug the mouse connector into
the MOUSE port, or you may damage your system.
If your system has not already been configured, you may need
to install a mouse driver. See your mouse manual for
instructions.
1-10 Setting Up Your System