anchor.diff:      if ( rst_file /= "" ) then
          inquire( file = rst_file, exist = file_exists )
          if ( .not. file_exists ) then
  -          write(0,*) '# ERROR # cannot access '//trim(rst_file)
  +          write(0,*) 'ERROR ! cannot access '//trim(rst_file)
             error_code = 1
             return
          end if
          call units_open_unf(rst_file,'old',urst,err)
          if( err /= 0 ) then
  -          write(0,*) '# ERROR # error opening file '//trim(rst_file)
  +          write(0,*) 'ERROR ! error opening file '//trim(rst_file)
             error_code = 1
             return
          end if
       end if
   
       if (uprm == 0 .and. urst == 0) then
  -       write(0,*) '# ERROR # either a rst or a prm file'
  +       write(0,*) 'ERROR ! either a rst or a prm file'
          error_code = 1
          return
       end if
   
       if( data_file == '' ) then
  -       write(0,*) '# ERROR # missing datafile'
  +       write(0,*) 'ERROR ! missing datafile'
          error_code = 1
          return
       else
          inquire( file = data_file, exist = file_exists )
          if ( .not. file_exists ) then
  -          write(0,*) '# ERROR # cannot access '//trim(data_file)
  +          write(0,*) 'ERROR ! cannot access '//trim(data_file)
             error_code = 1
             return
          end if
          ! open data file
          call units_open(data_file,'old',udata,err)
          if( err /= 0 ) then
  -          write(0,*) '# ERROR # error opening file '//trim(data_file)
  +          write(0,*) 'ERROR ! error opening file '//trim(data_file)
             error_code = 1
             return
          end if
  
positive.code:     if ( prm_file /= "" ) then
         inquire( file = prm_file, exist = file_exists )
         if ( .not. file_exists ) then
            write(0,*) '# ERROR # cannot access '//trim(prm_file)
            error_code = 1
            return
         end if
         call units_open(prm_file,'old',uprm,err)
         if( err /= 0 ) then
            write(0,*) '# ERROR # error opening file '//trim(prm_file)
            error_code = 1
            return
         end if
  
negative.code:           ! prm file
            call read_arg(iarg,nargs,prm_file,err)
            if (err == 1) then
               write(0,*) 'ERROR ! missing argument: '//trim(arg)//' <filename>'
               error_code = 1
               return
            end if
  