Informative components of w3c specifications

I know that it is possible to mark a section as informative
(class='informative').  In order to ensure that people using assistive
technologies (e.g., a screen reader) are aware they are in an informative
section, Mark Sadecki has suggested that the section be marked with a role
of 'region' and an aria-label of "informative".  With my "PFWG" hat on,
this makes sense and I was going to make this change in the aria.js
module...  Although I would prefer that the label be 'non-normative' to be
more consistent with the text that is injected into such sections.

However, it gives rise to another question.  Within W3C specifications
there are things *other than* sections that can be informative.  For
example, a 'note' is usually informative.  An 'editorial note' is certainly
informative.  Right now the aria.js module marks up notes with role="note"
- which I think makes sense.  But I might make sense to add an aria-label
of 'informative' or 'non-normative' on notes so that screen readers
correctly say something like "informative note start".

My question is "Are notes *always* informative?"  If not, "Are notes by
default informative, and should be annotated if they are normative?"  Or,
alternately, "should notes be required to have a class of 'informative' in
order to be marked as such?"

Opinions?