Library /sys$common/syshlp/basichelp.hlb Graphics, SET Statements, DEVICE_VIEWPORT  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  The SET DEVICE VIEWPORT statement lets you change  the  boundaries  of
  the  device  viewport, a portion of the display area.  Boundaries must
  be specified as device coordinates.

  Example

  ASK DEVICE VIEWPORT left_1,right_1,bottom,top
  !Set the device window to half of NDC space
  SET DEVICE WINDOW 0,0.5,0,1
  !Set the device viewport to the left half of the default
  SET DEVICE VIEWPORT left_1, right_1/2, bottom, top

  Additional Information (explode) :

• Syntax