Lexmark 302 - Manual (Page 160)

Document Insertion Device (F3)
F 3
F3
Clips Top of Forms Device
Bottom of Forms Device Finger Grips
The device has an F3 by itself in the upper left corner of the device.
Use this device for printing cut forms for correspondence, individual
invoice forms, and so on.
See “Installing and Using the Document Insertion Device (F3)” on
page 1-85 for information on installing and removing the forms
device, loading and unloading forms, and adjusting the device.
2-18 User’s Guide Model 302