anchor.diff:    !---------------------------------------------------------------------------------------------------------------------------------
     select case(f_out)
     case(f_out_ascii)
  -    write(unit=Unit_VTK,fmt='(A)',iostat=E_IO)repeat(' ',indent)//'<FieldData>' ; indent = indent + 2
  -    s_buffer = repeat(' ',indent)//'<DataArray type="Int64" NumberOfComponents="1" Name="'//trim(fname)//'" format="ascii">'// &
  +    s_buffer = repeat(' ',indent)//'<DataArray type="Int64" NumberOfTuples="1" Name="'//trim(fname)//'" format="ascii">'// &
                  trim(str(n=fld))//'</DataArray>'
       write(unit=Unit_VTK,fmt='(A)',iostat=E_IO)trim(s_buffer)
  -    indent = indent - 2 ; write(unit=Unit_VTK,fmt='(A)',iostat=E_IO)repeat(' ',indent)//'</FieldData>'
  -  case(f_out_binary)
  -    write(unit=Unit_VTK,iostat=E_IO)repeat(' ',indent)//'<FieldData>' ; indent = indent + 2
  -    s_buffer = repeat(' ',indent)//'<DataArray type="Int64" NumberOfComponents="1" Name="'//trim(fname)//'" format="ascii">'// &
  +  case(f_out_binary)
  +    s_buffer = repeat(' ',indent)//'<DataArray type="Int64" NumberOfTuples="1" Name="'//trim(fname)//'" format="ascii">'// &
                  trim(str(n=fld))//'</DataArray>'
       write(unit=Unit_VTK,iostat=E_IO)trim(s_buffer)
  -    indent = indent - 2 ; write(unit=Unit_VTK,iostat=E_IO)repeat(' ',indent)//'</FieldData>'
     endselect
     return
     !---------------------------------------------------------------------------------------------------------------------------------
  
positive.code:   !---------------------------------------------------------------------------------------------------------------------------------
    select case(f_out)
    case(f_out_ascii)
      write(unit=Unit_VTK,fmt='(A)',iostat=E_IO)repeat(' ',indent)//'<FieldData>' ; indent = indent + 2
      s_buffer = repeat(' ',indent)//'<DataArray type="Int8" NumberOfComponents="1" Name="'//trim(fname)//'" format="ascii">'// &
                 trim(str(n=fld))//'</DataArray>'
      write(unit=Unit_VTK,fmt='(A)',iostat=E_IO)trim(s_buffer)
      indent = indent - 2 ; write(unit=Unit_VTK,fmt='(A)',iostat=E_IO)repeat(' ',indent)//'</FieldData>'
    case(f_out_binary)
      write(unit=Unit_VTK,iostat=E_IO)repeat(' ',indent)//'<FieldData>' ; indent = indent + 2
      s_buffer = repeat(' ',indent)//'<DataArray type="Int8" NumberOfComponents="1" Name="'//trim(fname)//'" format="ascii">'// &
                 trim(str(n=fld))//'</DataArray>'
      write(unit=Unit_VTK,iostat=E_IO)trim(s_buffer)
      indent = indent - 2 ; write(unit=Unit_VTK,iostat=E_IO)repeat(' ',indent)//'</FieldData>'
    endselect
    return
    !---------------------------------------------------------------------------------------------------------------------------------
  
negative.code: 
    !> @ingroup Lib_VTK_IOPrivateProcedure
    !> @{
    !> Function for open/close field data tag.
    !> @return E_IO: integer(I4P) error flag
    function VTK_FLD_XML_OC(fld_action) result(E_IO)
    !---------------------------------------------------------------------------------------------------------------------------------
    implicit none
    character(*), intent(IN):: fld_action !< Field data tag action: OPEN or CLOSE tag.
    integer(I4P)::             E_IO       !< Input/Output inquiring flag: $0$ if IO is done, $> 0$ if IO is not done.
    !---------------------------------------------------------------------------------------------------------------------------------
  
    !---------------------------------------------------------------------------------------------------------------------------------
    select case(trim(Upper_Case(fld_action)))
    case('OPEN')
      select case(f_out)
      case(f_out_ascii)
        write(unit=Unit_VTK,fmt='(A)',iostat=E_IO)repeat(' ',indent)//'<FieldData>' ; indent = indent + 2
      case(f_out_binary)
        write(unit=Unit_VTK,iostat=E_IO)repeat(' ',indent)//'<FieldData>' ; indent = indent + 2
      endselect
    case('CLOSE')
      select case(f_out)
      case(f_out_ascii)
        indent = indent - 2 ; write(unit=Unit_VTK,fmt='(A)',iostat=E_IO)repeat(' ',indent)//'</FieldData>'
      case(f_out_binary)
        indent = indent - 2 ; write(unit=Unit_VTK,iostat=E_IO)repeat(' ',indent)//'</FieldData>'
      endselect
    endselect
    return
    !---------------------------------------------------------------------------------------------------------------------------------
    endfunction VTK_FLD_XML_OC
  
    !> Function for saving field data (global auxiliary data, e.g. time, step number, data set name...) (R8P).
    !> @return E_IO: integer(I4P) error flag
    function VTK_FLD_XML_R8(fld,fname) result(E_IO)
  