integral in the reverse direction

[Domingos Fernandes Urbano Neto <dfurbano@xxxxxxxxx>]

Dear Ferrets,

Im need comput integral from East to West, however I got confused with
the instructions in the Ferret's manual, which says:

Let integral = my_var[Y=lo:hi@IIN]

Let reverse_integral = my_var[Y=lo:hi@DIN] - my_var[X=lo:hi@IIN]

Is it realy "X" in the second part of the equation?

Thanks,

Domingos.