A pivot (PLAN ยง11.12): its row columns, its pivot column ('' until picked),
its values as typed literals {kind, value}, in order, and its aggregation
{column, function}, the column left out for Count rows. Texts are kept as
saved, '' included, for validation to judge. A value that isn't a literal
this version reads, or a key it doesn't know, could change the rows, so it
makes the node unreadable.
A pivot (PLAN ยง11.12): its row columns, its pivot column (
''until picked), its values as typed literals{kind, value}, in order, and its aggregation{column, function}, the column left out for Count rows. Texts are kept as saved,''included, for validation to judge. A value that isn't a literal this version reads, or a key it doesn't know, could change the rows, so it makes the node unreadable.