QuarkXPress allows you to drag the origin (zero) point of its rulers to anywhere on your document page, thus changing the location from which items are measured. Just drag the square where the rulers meet down onto your document page to set its new origin.
To restore the origin to its original position, just Option-click that same square. (Windows: Alt-click)
Jay Nelson is the editorial director of PlanetQuark.com, and the editor and publisher of Design Tools Monthly. He’s also the author of the QuarkXPress 8 and QuarkXPress 7 training titles at Lynda.com, as well as the training videos Quark includes in the box with QuarkXPress 7 . In addition, Jay writes regularly for Macworld and Photoshop User magazines and speaks at industry events.