I have different dates that I need to classified with different codes. The
codes are M-00, M-01, M-02, M-03, M-04, M-05, M-06, M-07, M-08, M-09, M-10,
M-11, M-12, M+01, M+02, M+03, M+04, M+05, M+06, M+07, M+08, M+09, M+10, M+11,
and M+12.
To gave a code this is the criteria:
Today's date is M-00, but is not only for today's date is for all the month
that today's date contained.
For example: 8/21/09 is M-00, but also for all the month of August will be
M-00.

Now this is the trick, as soon as September starts, September will be M-00.

M-00 means that we are on the month that we need to accomplish the task
M-01 means that we are 1 month away to acomplish the task
M-02 means that we are 2 months away to acomplish the task
M-03 .........
Now,
M+01 means that we are one month behind of that task
M+02 means that we are two months behind of the task
M+03 .......

Let me expose you some examples of code assigned already assuming that we
are on August as M-00.

8/5/09 M-00
8/20/09 M-00
9/6/09 M-01
10/5/09 M-02
11/9/09 M-03
12/12/09 M-04....................
7/09/09 M+01
6/8/09 M+02
5/5/09 M+03

Next month, August will be M+01 and September will be M-00.

How can I create a formula that as soon as change the today's date all the
codes change automatically.

Thank you
Loulou