"charset" is not generic to all media types [nsMediaType-3]

The diagram
  http://www.w3.org/2001/04/roadmap/xml-charset.svg
  http://www.w3.org/2001/04/roadmap/xml-charset.n3

suggests that one can look for a "charset" parameter
on any XML document in a MIME body part; i.e.
that the semantics of parameters named "charset"
is shared across all media types.

I wondered whether that's the case, which
earned me...

"Action DC: Verify that parameter names are local
to each MIME type."
  -- http://lists.w3.org/Archives/Public/www-tag/2002Jan/0235

Indeed...

[[[
For example, the "charset" parameter is applicable to any subtype of
   "text", while the "boundary" parameter is required for any subtype of
   the "multipart" media type.
  There are NO globally-meaningful parameters that apply to all media
  types
 ]]]
  -- http://www.ietf.org/rfc/rfc2045.txt

Perhaps it's cost-effective to change this; after all,
it seems silly for somebody to define a media type
with a parameter named "charset" that means something else.
But as it is, the algorithm in the diagram relies
on more than the specs guarantee.

-- 
Dan Connolly, W3C http://www.w3.org/People/Connolly/