The Unprintable Regions control contains two boxes which specify the height of the unprintable regions found at the top and bottom of a page of paper. These values specify the amount of space that becomes unprintable due to the paper-feed mechanism. Typically, sheet feeders will be the only type of paper source that introduces an unprintable region. (These values are not the same values entered in the Paper Sizes dialog box.)
For the Diconix 150 Plus printer, the paper-feed mechanism does not create a unique unprintable region; therefore, the Top and Bottom boxes contain the value -1.
For the HP LaserJet IIP printer, the paper-feed mechanism does not create a unique unprintable region; therefore, the Top and Bottom boxes contain the value -1.