Media types for RDF languages N3 and Turtle

Hi all, there are a couple languages that have been used for a while,
turtle and n3, and I am trying work out the right media types to
register for them.


== Cast of Characters
╔══════════╦══════════════════════════════╦══════════════════════╗
║  name    ║            role              ║  current media type  ║
╠══════════╤══════════════════════════════╤══════════════════════╣
║ RDF      │ data model                   │ N/A                  ║
╟──────────┼──────────────────────────────┼──────────────────────╢
║ RDFXML   │ XML serialization of RDF     │ application/rdf+xml  ║
╟──────────┼──────────────────────────────┼──────────────────────╢
║ ntriples │ simple serialization of RDF  │ text/plain           ║
╟──────────┼──────────────────────────────┼──────────────────────╢
║ turtle   │ textual serialization of RDF │ application/x+turtle ║
╟──────────┼──────────────────────────────┼──────────────────────╢
║ n3       │ extension¹of turtle language │ text/rdf+n3 (not     ║
║          │ expressing a superset of RDF │          registered) ║
╚══════════╧══════════════════════════════╧══════════════════════╝ 

¹ The origins of turtle and n3 are complicated, but this is the
  most practical model for media type consideration.

These languages will be published under http://www.w3.org/TR/
(which implies certain persistance and update policy) as soon
as I work out what to include in the media type registration.
In the mean time, see
  http://www.dajobe.org/2004/01/turtle/#sec-mime
  http://www.w3.org/DesignIssues/Notation3

Neither the turtle nor n3 media types are registered. I seek advice
from the community on exactly how to register them, as I will have
to beat out some sort of consensus in order to register them.


== Issues
• subsumption relationshop — n3 subsumes turtle in both data model and
  grammar. To that end, text/n3; and text/n3; profile=turtle have been
  suggested. Another suggestion has been text/rdf+n3 and
  text/rdf+turtle , in somewhat the spirit of XML (where the +xml
  indecates the that it's the XML encoding of the preceding datatype).

• subtree — turtle and n3 are certainly more human-readable than
  ntriples (as they are basically extensions of ntriples, with
  namespace prefixes and abbreviations for some atoms). The default
  character encoding of iso-8859-1 is certainly outdated, and doesn't
  make sense for any of these languages. Garret Wilson (Cc'd) raised
  the question of whether a text/ registration may force the charset
  to be, say, utf-8². Both n3 and turtle, as well as related langs
  like SPARQL, are explcitly utf-8. Can the registration include text
  like "The encoding is always UTF-8"? Would that mean that the
  media type would not need a constant charset parameter?

² http://lists.w3.org/Archives/Public/www-rdf-comments/2007OctDec/0017


== Strawman
Let me propose:
  n3: text/rdf+n3
  turtle: text/rdf+turtle
with
[[
Encoding considerations: The encoding is always UTF-8
]]
and the expectation that
[[
Content-type: text/rdf+n3
]]
(or +turtle) fully specifies the media type and the
character encoding.


A plea to all: bear in mind that this consensus bit is a hard job,
and that the world will be much better off if we can reach a timely
compromise. We've suffered for five years without these media types
so let's keep our mission reallistic.
-- 
-eric

office: +1.617.258.5741 NE43-344, MIT, Cambridge, MA 02144 USA
mobile: +1.617.599.3509

(eric@w3.org)
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