Legacy VTK: associating multiple unknowns with each point

Hi, I might have missed something obvious in the documentation, but it is not clear to me how I can associate multiple (say, up to 20) scalars with each point in a legacy VTK STRUCTURED_POINTS representation.

Currently I would write the heading of a 2D leg.VTK file as follows

# vtk DataFile Version 3.0
insert some description of the data here
DIMENSIONS 297 297 1                                                        
ORIGIN 0.000925926 0.000925926 0.000925926
SPACING 0.0033607685993265997 0.0033607685993265997 0.0033607685993265997

And then have 4 POINT_DATA fields each defining a single variable for each point in the above defined topology:

SCALARS unknown_<var num.> float 1
LOOKUP_TABLE unknown_<var num.>_table
<88209 floats now follow>

I guess this is probably the wrong way to associate multiple variables with individual points in legacy VTK as I can only view the first POINT_DATA field - i.e. unknnown_1 - in paraview. It returns the following error when loaded into paraview:

ERROR: In /opt/glr/paraview/paraview-ci/build/superbuild/paraview/src/VTK/IO/Legacy/vtkDataReader.cxx, line 1007
vtkStructuredPointsReader (0x7fbc4d6f8810): Unsupported point attribute type: point_data for file: vtk_file.vtk

What is the correct way?

Thank you for any guidance.