Apple Power Macintosh 4400 - Manual (Page 154)

The communication slot and the cards that fit in it are often referred to as
“Apple Comm Slot II” or “CS II” devices. Be sure to use a card that is Apple
Comm Slot II-compliant; earlier versions of Ethernet cards will not work in
this slot.
Some communication cards designed for other communication slots are not
compatible and cannot be installed here. You can tell by examining the
placement of the notches on the card. Use the following illustration as a guide
if you’re not sure you have the correct type of card.
Compatible
Compatible
Notches Communication card
Notches
Not compatible
Notches
154 Chapter 10