Tag hierarchy idea redux -- thesaurus -- Feature request

[John Tait <johngtait@gmail.com>]

Dear all

Some time ago I floated a "tag hierarchy" idea for org-mode. It didn't
gain much interest.

http://lists.gnu.org/archive/html/emacs-orgmode/2011-03/msg01393.html

What I've discovered since then is that I was trying to reinvent both
a thesaurus concept and a controlled vocabulary concept. Thesauri seem
to be well understood, and is standardised by ISO 2788.

What I am looking for then is a way of managing org tags using a very
simple thesauri idea -- inside an org file.

The problem I've trying to solve is that, in big publishing projects,
the number of tags can grow and might eventually need to be managed
outside org-mode.

What I would love to do is build a simple taxonomy of tags from a
controlled vocabulary that I can manage entirely inside org-mode.

Then we could:
  a) have an orderly list of tags (using the "USE" concept, etc.) to
restrict tag bloat.
  b) allow nesting of tags (using the BT and NT concepts). This would
allow export of, say, :colour: to export :red: :green: and :blue:. It
would also allow the BT tags to be managed rather than micromanaging
tags in headings. Additionally, tags could belong to more than one
taxonomy in the same publishing project.

(The dreaded DITA 1.2 spec now has something like this in the guise of
Subject Scheme maps. Please don't make me look at DITA again..!)

http://docs.oasis-open.org/dita/v1.2/cs01/spec/common/subjectScheme.html

I hope you know what I am on about...thanks again for your time.

John Tait