Comparison chaining (0 < x <= 1) or BETWEEN function
One of the early but forgotten disappointments of any Excel user is that you can't do this:
0 < A1 <= 1
You have to break it up like this:
otherwise Excel will evaluate 0 < A1 and check if that is <= 1.
Since we rarely want this case, why not interpret 0 < A1 <= 1 as the user intended? It would make formulas more readable and avoid repetition. Of course, this can be extended to all comparison operators (<, >, <>, <=, >=, =) and for an arbitrary number of them in a row (e.g. 1 < i <= j < n). "Not between" would simply be NOT(0 < A1 <= 1).
Alternatively, have a function BETWEEN(v1,c1,v2,c2,...) where v are the values in ascending order and c are either TRUE for <= or FALSE for <.
Kenneth Barber commented
On second thought, c should have 3 values: <, <=, =.