These are the atoms to use when creating contexts to specify the device:
$LFDisplay The default one-bit-per-pixel black-and-white display.
$ColorDisplay The default color display, in whatever mode it is in right now.
$PDHornet For a PD file for a 384 dots-per-inch, vertically scanned printer.
$PDPuffin For a PD file for a 384 dots-per-inch, horizontally scanned 3-color printer.