R: R: general question

Santoni Adriano Adriano.Santoni at actalis.it
Mon Mar 9 10:36:05 CET 2009

Thank you,


-----Messaggio originale-----
Da: Magnus Westerlund [mailto:magnus.westerlund at ericsson.com] 
Inviato: lunedì 9 marzo 2009 10.30
A: Santoni Adriano
Cc: Roni Even; ietf-types at alvestrand.no
Oggetto: Re: R: general question

Santoni Adriano skrev:
> Roni,
> thank you for replying.
>>> Are you asking if the media type registration need to be in the same
> document as the payload specification
> Yes, exactly.
>>> Look in RFC 4855 ........ there it says that registration and the
> payload specification can be different documents.
> Indeed, but some may argue that RFC4855 is related to the RTP 
> (Real-time Transport Protocol) case only.
> RFC 4288, which is mote general, seems to state the opposite at par. 4.10:
>     "Proposals for media types registered in the standards tree by the 
> IETF itself MUST be published as RFCs."

There is plenty of cases where the Media Registration is done in one document and the specification of the format is in another. And the above rule you are citing is only saying that the media types registered by IETF needs to be published in an RFC. It doesn't put any requirement on them being the same.

> So it is still not clear (to me) if RFC 4855 is an exception to the 
> general rule, or not.
>>> I am not sure that I know of such cases...
> I think you are right. After a closer examination of several cases, I 
> have always found a (sort of) media type registration in each of them.
> Again, I wonder if a media type can be registered after the payload 
> specification has been published; it may not always be clear, at the 
> payload specifications' publication time, that a corresponding new 
> media type is also needed.

So registration of media types for files etc can definitely be done later and in separate documents. See RFC 3839 when this is done for a format that is specified outside of IETF.


Magnus Westerlund

IETF Transport Area Director & TSVWG Chair
Multimedia Technologies, Ericsson Research EAB/TVM
Ericsson AB                | Phone  +46 10 7148287
Färögatan 6                | Mobile +46 73 0949079
SE-164 80 Stockholm, Sweden| mailto: magnus.westerlund at ericsson.com

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