Canon PIXM MX300 Series User Manual page 23

Platen Glass.
Place the original in landscape orientation and align the upper corner of it with the
alignment mark as shown in the figure above.
Important
Do not place any objects weighing more than 4.4 lb / 2.2 kg on the
Platen Glass.
Do not press or put weight on the original with pressure exceeding
4.4 lb / 2.2 kg.
Doing so may cause the scanner to malfunction or the Platen Glass to
break.
Note
The machine cannot scan the area in red in the figure below.
0.04 inches / 1 mm
(A)
When copying, the area you can scan depends on the printable area
of the media. See
2
Gently close the Document Cover.
Printing Area.
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