I'd like to know a little more about margins and placement with the Impose tool. The documentation doesn't indicate how margins are to be specified, or whether they're placed around each original page or bound the layout of the new single page.
It also does not indicate how to specify the size of the margin; through trial and error, I've found that units need to be specified (e.g. "0.5in" or "1cm" works) but it would be helpful to list the units available (pixels? points?).
As far as I can tell, the n-upping a file (going from letter-size portrait to landscape, in the cases I've tried) always puts the original pages at the *bottom* of the new page. This is different from most n-up tools, such as psnup, which center things on the page. It would be great to make this possible, since it is probably what a lot of users would want to print out (rather than something running all the way to the bottom margin).
Another way of achieving this would be to specify the four margins more independently (it would thus be possible to create the centering manually; this is not possible by specifying only a single value for all margins.
Finally, there's an error in the documentation for Impose: it states, "The imposition is named with -im appended to the original file name." In actuality "-up" is appended.