! Copyright 2005-2018 ECMWF.
!
! This software is licensed under the terms of the Apache Licence Version 2.0
! which can be obtained at http://www.apache.org/licenses/LICENSE-2.0.
! 
! In applying this licence, ECMWF does not waive the privileges and immunities granted to it by
! virtue of its status as an intergovernmental organisation nor does it submit to any jurisdiction.
!
!
!
!  Description: how to set missing a key value.
!
!
!
program set
  use grib_api
  implicit none
  integer              :: infile,outfile
  integer              :: igrib, Ni, is_missing

  infile=5
  outfile=6

  call grib_open_file(infile, &
       '../../data/reduced_gaussian_pressure_level.grib2','r')

  call grib_open_file(outfile, &
       'out_surface_level.grib2','w')

  !     a new grib message is loaded from file
  !     igrib is the grib id to be used in subsequent calls
  call grib_new_from_file(infile,igrib)

  call grib_set(igrib,'typeOfFirstFixedSurface','sfc')
  call grib_set_missing(igrib,'scaleFactorOfFirstFixedSurface')
  call grib_set_missing(igrib,'scaledValueOfFirstFixedSurface')
  
  ! See GRIB-490
  call grib_get(igrib, 'Ni', Ni)
  call grib_is_missing(igrib,'Ni',is_missing)
  if ( is_missing == 0 ) then
    ! Ni should be missing in gribs with Reduced Gaussian grids
    call grib_check(-2, 'Ni_should_be_missing', '')
  endif
  call grib_set(igrib, 'Ni', Ni)

  call grib_write(igrib,outfile)
  call grib_release(igrib)
  call grib_close_file(infile)
  call grib_close_file(outfile)

end program set
