So a left-to-right listing of (colon-separated) tags after the heading cannot imply a higher-to-lower hierarchical order? So there is no hierarchy unless you create it, e.g.,
-- is what I'm hearing.
What I meant to do is to be able to use tags alone or together. And when used together, to somehow imply hierarchy. So if I have
* header 1 :emacs:
** header 1.1 :orgmode:
*** header 1.1.1 :lisp:
stuff about Emacs' org-mode's lisp code
this implies subject hierarchy simply from the headers' hierarchy. However this
* header 1 :emacs:
stuff about Emacs
* header 2 :emacs:orgmode:lisp
stuff about Emacs' org-mode's lisp code
* header 3 :lisp:
stuff about just Common Lisp
* header 4 :emacs:orgmode:
stuff about Emacs' org-mode
* header 5 :emacs:
more stuff about Emacs
is all peers header-wise, while the tags (if using left-to-right listing to mean higher to lower in hierarchy) tell us the depth level of specialization of a topic. The first set of headers is relying (clumsily) on the header level to indicate depth of specialization, which is not always realistic. If I wanted, ad-hoc, to indicate levels of some hierarchy with tags, that is, not be forced to create empty superior headers, it seems there's no prescribed way to do this. And creating tag hierarchies by hand, i.e., (setq org-tag-alist '((:startgrouptag)..., makes me play the combinatorics game of imagining all different possible hierarchy combinations. Or am I missing something?