Given
c1 = <|"Ca" -> "ca1", "Cb" -> "cb1", "Cc" -> "cc1"|>;
c2 = <|"Ca" -> "ca2", "Cb" -> "cb2", "Cc" -> "cc2"|>;
row1 = <|"A" -> "a1", "B" -> "b1", "C" -> c1, "D" -> "d1"|>;
row2 = <|"A" -> "a2", "B" -> "b2", "C" -> c2, "D" -> "d2"|>;
Dataset[{row1, row2}]
What is the optional argument to Dataset to force it to generate a nested inner-header as in the following image:
What follows is a longer format for the question above, and the unexpected finding that inserting a Quantity value in each row encourages Dataset to display the nested header correctly.
