Xerox 850DX - Phaser Color Solid Ink Printer User Manual page 67

Scale to Fit - Select the Scale to Fit box to have the size of each
constituent page adjusted to fit its entire allocated space on the Canvas.
This also causes the Scale to Fit box to be selected on the individual
documents' Composition tab.
NOTE: Auto Compose and Scale to Fit need to be selected when you add
more documents to an open set to which you have already applied these
options. The Auto Compose checkbox will be unselected upon any entry to
the Job Print Options Dialog.
AccXES Client Tools User Guide 67