Xerox M20/M20i manual Clock Mode, Actual size. Margins can be set between 30mm

OPTION	SETTINGS	DESCRIPTION	Administration
Clock Mode	12 hour	The machine can be configured to display time
		using either a 12-hour or 24-hour format.
	24 hour
Toner Save	On	If On, the machine produces a lower quality	Machine
		only.
		output to reduce toner consumption. Useful if
	Off	your machine is used for internal documents
Discard Size	[00 - 30]	If the Fax Setup option Auto Reduction is set to
		Off, and the received document is as long or
		longer than the paper selected, the machine will
		discard any excess image from the bottom of
		the page that is longer than the selected length.
		If the received page is outside the discard
		margin set, it will print on two sheets of paper at
		the actual size. Margins can be set between 0 -
		30mm (1.2").

Xerox CopyCentre C20, WorkCentre M20 and WorkCentre M20i User Guide Page 9-5