Clarification on setting reference_ellipsoid_name, prime_meridian_name, horizontal_datum_name and geographic_crs_name

[snowman2]

In the notes of Appendix F it states:

Notes:

1.    The various *_name attributes are optional but recommended when known as they allow for a better description and interoperability with WKT definitions.

2.    reference_ellipsoid_name, prime_meridian_name, horizontal_datum_name and geographic_crs_name must be all defined if any one is defined, and if projected_crs_name is defined then geographic_crs_name must be also.

If I have this WKT with undefined projected crs name and undefined geographic CRS name:

PROJCRS["unknown",
    BASEGEOGCRS["unknown",
        DATUM["Unknown based on Normal Sphere (r=6370997) ellipsoid",
            ELLIPSOID["Normal Sphere (r=6370997)",6370997,0,
                LENGTHUNIT["metre",1,
                    ID["EPSG",9001]]]],
        PRIMEM["Greenwich",0,
            ANGLEUNIT["degree",0.0174532925199433],
            ID["EPSG",8901]]],
    CONVERSION["unknown",
        METHOD["Hotine Oblique Mercator (variant B)",
            ID["EPSG",9815]],
        PARAMETER["Latitude of projection centre",0,
            ANGLEUNIT["degree",0.0174532925199433],
            ID["EPSG",8811]],
        PARAMETER["Longitude of projection centre",13.8096029486222,
            ANGLEUNIT["degree",0.0174532925199433],
            ID["EPSG",8812]],
        PARAMETER["Azimuth of initial line",8.99811271718794,
            ANGLEUNIT["degree",0.0174532925199433],
            ID["EPSG",8813]],
        PARAMETER["Angle from Rectified to Skew Grid",0,
            ANGLEUNIT["degree",0.0174532925199433],
            ID["EPSG",8814]],
        PARAMETER["Scale factor on initial line",1,
            SCALEUNIT["unity",1],
            ID["EPSG",8815]],
        PARAMETER["Easting at projection centre",0,
            LENGTHUNIT["metre",1],
            ID["EPSG",8816]],
        PARAMETER["Northing at projection centre",0,
            LENGTHUNIT["metre",1],
            ID["EPSG",8817]]],
    CS[Cartesian,2],
        AXIS["(E)",east,
            ORDER[1],
            LENGTHUNIT["metre",1,
                ID["EPSG",9001]]],
        AXIS["(N)",north,
            ORDER[2],
            LENGTHUNIT["metre",1,
                ID["EPSG",9001]]]]

Is it recommended to represent with all *_name attributes with the missing ones denoted as undefined:

projected_crs_name: 'undefined'
geographic_crs_name: 'undefined'
semi_major_axis: 6370997.0,
semi_minor_axis: 6370997.0,
inverse_flattening: 0.0,
reference_ellipsoid_name: 'Normal Sphere (r=6370997)',
longitude_of_prime_meridian: 0.0,
prime_meridian_name: 'Greenwich',
horizontal_datum_name: 'Unknown based on Normal Sphere (r=6370997) ellipsoid',
grid_mapping_name: 'oblique_mercator',
latitude_of_projection_origin: 0.0,
longitude_of_projection_origin: 13.809602948622212,
azimuth_of_central_line: 8.998112717187938,
scale_factor_at_projection_origin: 1.0,
false_easting: 0.0,
false_northing: 0.0

Or to remove all of the *_name attributes:

semi_major_axis: 6370997.0,
semi_minor_axis: 6370997.0,
inverse_flattening: 0.0,
longitude_of_prime_meridian: 0.0,
grid_mapping_name: 'oblique_mercator',
latitude_of_projection_origin: 0.0,
longitude_of_projection_origin: 13.809602948622212,
azimuth_of_central_line: 8.998112717187938,
scale_factor_at_projection_origin: 1.0,
false_easting: 0.0,
false_northing: 0.0

[snowman2]

I am planning to go with the first one where the ones that are unknown will be denoted as unknown for now.

[JimBiardCics]

@snowman2 I've got no problem with using unknown, but I think missing should be considered equivalent.

[snowman2]

@JimBiardCics, thanks for your response, that is very helpful. We will plan on leaving the value that was in the CRS WKT in the *_name.