Shame it doesn't work :(
Some aritmetric operations are defined, which has a meaning that may seem strange at first, but they are natural for usage purposes.
Adding/Subtracting number of days from a data:
d=d1+7 gives d the date 7 days after date d1.
d=d1-7 gives d the date 7 days before date d1.
Finding the number of days between 2 dates. i=d1-d2. Here i is an integer that is the number of days between d1 and d2. i will be negative if d1 d2.
date d1(30,6,1993); date d2(19930610);
i = d1-d2
Gives i the value 20, the number of days between 10 jun 93 and 30 jun 93.