Although PDFClerk Pro will always render imposed layouts by their
media box, the layout engine can be made to automatically define any
of the other display boxes on each imposed sheet. It does this
according to the settings in the imposition template for the imposed
layout. After the laying out the imposition, display boxes may be
adjusted for each sheet individually by using the Display Boxes
inspector. Note, however, that if you change imposition mode after
manually adjusting display boxes, you will lose those modifications.
PDFClerk Pro will warn you of this when you try to switch away from an
imposition which defines secondary display boxes. See the chapter on
Impositions starting on starting page 38 for more information on
display boxes on imposed layouts and the entry on the
Inspector, for more information on display box editing.