org-mode time spreadsheet

[Deniz Dogan <deniz.a.m.dogan@gmail.com>]

I hope this formats well, because I'm posting this through Google
Groups... Anyways...

Hi

I'm trying to have an org-mode table which shows a working day (not
necessarily every normal work day, I enter these myself) and when I
got in, when I went out to lunch, when I came back, and when I left
for the day. I want the last column "TOT" to display how long I was at
work minus the time I was out for lunch.

I'm well aware of timeclock-in, timeclock-out, as well as org-mode's C-
c C-x C-i/C-o functionality, but I really want to have it as a
spreadsheet. However, it seems that calc isn't that good at working
with times, so now I'm asking you for help. Is this possible to do
with plain org-mode? If so, what am I doing wrong? Below is the file
I'm currently using and it seems that it doesn't realize that the
values are actually timestamps.

| DATE       |    IN | LUNCH FROM | LUNCH TO |   OUT | TOT    |
|------------+-------+------------+----------+-------+--------|
| THU 18 NOV |  9:30 |      12:30 |    13:40 | 14:20 | 2:5    |
| FRI 31 DEC | 10:00 |      12:00 |    14:00 | 16:00 | #ERROR |
| SAT 1 JAN  |  8:00 |      12:00 |    12:30 | 16:00 | #ERROR |
| MON 5 JAN  |  9:00 |      12:45 |    13:15 | 16:00 | #ERROR |
| TUE 6 JAN  | 16:30 |      17:30 |    18:30 | 22:30 | 1:5    |
| WED 7 JAN  |  9:00 |      12:00 |    12:40 | 20:45 | 11:05  |
| THU 8 JAN  | 12:30 |      15:00 |    15:40 | 18:30 |        |
| FRI 9 JAN  |  9:00 |            |          |       |        |
#+TBLFM: $6=$5-$2

Deniz