! Set up VD: units with ADVD, assuming VDDRIVER is already
! loaded somewhere.
DEFINE VERB ADVD
   IMAGE VD$DST:ADVD.EXE
     parameter p1,prompt="VDn:",value(required,type=$device),label=UNIT
     parameter p2,label=FNAM,prompt="file",value(type=$infile)
     qualifier ASSIGN
     qualifier DEASSIGN