Impose+ is a collection of postscript tools that serve as interfaces to psutils. They aid in creating postscript files with ease, and are designed to simplify the printing and presentation process.
Impose is the utility used for two-up printing of DSC compliant postscript files from programs like Netscape, dvips, and Openoffice. It eliminates white space from printouts by probing the original postscript to determine the bounding box of the printed area. Unlike simplistic layouts of non-cropped original papers done by psnup (part of the psutils package), impose produces more esthetic output. This is apparent in the accompanying example that displays images of output from both psnup and impose. While psnup produces simplistic tiling of the entire page, impose output eliminates white space, resulting in a file with more text.
Psbl, on the other hand, acts as a frontend to impose and is primarily used for booklet printing. It performs several tasks, including splitting documents with an excess of pages into multiple 'signatures,' rearranging pages within the signature, calling impose on the result, and inserting postscript instructions that enable a printer to tumble the output, resulting in an esthetic booklet.
Fixtd adds postscript instructions that ask the printer to turn on tumbling and duplex options, resulting in higher quality printouts.
Bboxx calculates the individual and global bounding boxes of a postscript file. This utility has recently been rewritten to use ghostscript's recently introduced bbox device.