[Orgmode] Adding tags, grouping tags

[Karl Maihofer]

I'd like to define many many tags and use numerics (1-0) as selection
keys. I want to define tags for different clients, people, gtd-contexts,
and other contexts. So I had the idea to group the tags (less than ten
tags per group) to be able to define selection keys for every tag.

I already use groups for my custom agenda views (see example below). So
when I hit C-c a, Org only shows the agenda groups (besides the default
agenda commands) and I do not get to the actual agenda commands until I
hit Q. This enables me to use the keys 1, 2, 3, 4 several times for
different agenda commands (in different groups).

Example:

(setq org-agenda-custom-commands
   '(("Q" . "Custom queries") ;; gives label to "Q"
     ("Q1" "Archive search" search ""
      ((org-agenda-files (file-expand-wildcards "~/archive/*.org"))))
     ("Q2" "Website search" search ""
      ((org-agenda-files (file-expand-wildcards "~/website/*.org"))))
     ("Q3" "Projects and Archive" search ""
      ((org-agenda-text-search-extra-files (file-expand-wildcards
"~/archive/*.org"))))
             ;; searches both projects and archive directories
     ("Q4" "Archive tags search" org-tags-view ""
      ((org-agenda-files (file-expand-wildcards "~/archive/*.org"))))
     ;; ...other commands here
      ))

Is something similar possible for adding tags?