%!demo
%! ## `isordinal` reports whether the categories carry an order.  A plain array is
%! ## *nominal* — its categories are just labels with no ranking ...
%!
%! N = categorical ({'red'; 'green'; 'blue'})
%! isordinal (N)
%!
%! ## ... while one built with `'Ordinal', true` is ordered, which is what lets it
%! ## be compared with `<` and `>` and sorted meaningfully.
%!
%! O = categorical ({'lo'; 'hi'; 'mid'}, {'lo', 'mid', 'hi'}, 'Ordinal', true)
%! isordinal (O)
