History of Up

	Revision 3 . . (edit) September 29, 2001 8:32 am by Bryan Derksen
	Revision 2 . . September 29, 2001 6:39 am by (logged).21.188.xxx [Clarifying the difference between up and down]
	Revision 1 . . September 29, 2001 6:33 am by (logged).21.188.xxx

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Difference (from prior major revision) (minor diff, author diff)

Changed: 1c1

What is "up"?

"Up" describes the positive z-value in a gravitational field, just as "down" represents the negative z-value. The z-axis is the only axis that is not apparently arbitrary. The x and y values, "North", "South", "East", and "West" do in fact exist (and are named relative to the direction of the Earth's spin) but are not readily apparent.