Int 2A Fn 8700  CU - Print - Begin Background Printing                     [P]

   AX = 8700h
   CF clear

Return: CF clear if OK to print in background now
   CF set if background printing not allowed at this time
Desc:  used to inform interested programs that PRINT is about to start its
     background processing, and allow those programs to postpone the
     processing if necessary

Notes: when PRINT gains control and wants to begin printing, it calls this
     function.  If CF is clear on return, PRINT begins its background
     processing, and calls AX=8701h when it is done.  If CF is set on
     return, PRINT will relinquish control immediately, and will not
     call AX=8701h
   PCVENUS (an early network shell by IBM and CMU) hooks this call to
     prevent background printing while its own code is active

See Also: AH=80h,AH=81h,AX=8701h