SELECT NULL AS "Literal Null Value", pg_typeof(null) AS "Type of Null", pg_typeof(NuLl::text) AS "Type of Cast null", cast(null as text) AS "Cast null value";
should be
pg_typeof(null::text) AS "Type of Cast Null",
That was not a typo. I'm intentionally showing an example demonstrating that the SQL NULL is fully case-insensitive. But I suppose showing both all-upper and all-lower cases fulfills that goal sufficiently. Changed. Went with NULL so there are two of each. Made all of the column headers Title Case.
