Filter weekly/daily agenda by tag

[Alexander Baier <lexi.baier@gmail.com>]

Hello,

this is my first post on the mailing list and i am not quite sure if i
do everything right. If i screw something up, please let me know, so i
can fix it and do it right next time.

To the problem I'm facing:

My setup: I have a single org file with appointments as sub trees.
Each appointment has an active timestamp assigned to it, so it appears
in the weekly agenda view. It also has one or more tags assigned to
it.
The agenda view i want to create: I would like to have a weekly agenda
view filtered by the tags assigned to the events.

Now, i searched the org-mode list archives and found this post:
http://lists.gnu.org/archive/html/emacs-orgmode/2011-08/msg00812.html
where Bernt Hansen writes "You should be able to achieve this by
setting the variable
org-agenda-filter.". Where does this variable org-agenda-filter come
from? If i want to describe it in emacs, i cannot find it. So i think
this is a setting which can be passed to commands in
org-agenda-custom-commands. (btw: is there a place where all the
settings i can pass to these commands is documented?) I created my own
agenda-command in my .emacs, but it did not filter the weekly agenda
view as described above. This is my code:
(setq org-agenda-custom-commands
  '(("d" "Test Tag Filter"
     ((agenda ""
              ((org-agenda-files '("~/org/WeeklyFilterTest.org"))
               (org-agenda-filter "-EXCL")))))))

And this is my ~/org/WeeklyFilterTest.org:
* Events
  :PROPERTIES:
  :CATEGORY: Event
  :END:
** Event1                                                              :INCL:
  <2012-10-29 Mon>
** Event2                                                              :INCL:
  <2012-10-30 Tue>
** Event3                                                              :EXCL:
  <2012-10-30 Tue 18:00>
** Event4                                                              :INCL:
  <2012-10-30 Tue 19:00>

To explain what i want to achieve regarding this example: I want a
weekly agenda view only displaying Event1, Event2 and Event4 but not
Event3 as it should be excluded by its tag.

Any help is appreciated.

Regards
Alexander