Define verb FDHOSTboh
  Image sys$system:fdhostboh.exe
  Parameter p1,prompt="FDn:",value(required,type=$device),label=UNIT
  parameter p2,label=FNAM,prompt="file",value(type=$infile)
  qualifier CLEAR
! Note: CLEAR switch is for FDHOST.MAR only. It just zeroes the
! reference count of the FD: unit in case aborting control tasks
! left this nonzero.
! Uses FDHOST image to create a memory disk for fd0: (test case)
! or generally...