Reverse integral

[Domingos Fernandes Urbano Neto <dfurbano@xxxxxxxxx>]

Dear Ferrets,

Im need to comput the integral from East to West, although 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? Or the correct is
Y at the IIN?
Is this the same as do "reserse integral iqual minus integral"?

Thanks,

Domingos.