COMDISK 
COMMON
DISKINS ' DISK INSTALLATION DESIRED (YES/NO)   '=(*N=NO,YES,NO),
UN1     ' ALTERNATE USER NUMBER FOR INPUT PL   '=(*N=0,*F), 
UN2     ' ALTERNATE USER NUMBER FOR OUTPUT PL  '=(*N=0,*F), 
OUTPRD  ' WRITE OUTPUT PROGRAM LIBRARY         '=(*N=NO,YES,NO),
