RFC Errata
RFC 5688, "A Session Initiation Protocol (SIP) Media Feature Tag for MIME Application Subtypes", January 2010
Source of RFC: IETF - NON WORKING GROUPArea Assignment: rai
Errata ID: 1997
Status: Held for Document Update
Type: Editorial
Publication Format(s) : TEXT
Reported By: Alfred Hoenes
Date Reported: 2010-01-10
Held for Document Update by: Robert Sparks
Throughout the document, when it says:
a) document title:
A Session Initiation Protocol (SIP) Media Feature Tag for MIME
Application Subtypes
b) Abstract
The caller preferences specification for the Session Initiation
Protocol (SIP) allows a caller to express preferences that the call
be routed to a User Agent (UA) with particular capabilities.
Similarly, a specification exists to allow a UA to indicate its
capabilities in a registration. Amongst those capabilities are the
| type of media streams the agent supports, described as top-level MIME
| types. The 'application' MIME type is used to describe a broad range
of stream types, and it provides insufficient granularity as a
capability. This specification allows a UA to indicate which
application subtypes the agent supports.
c) Section 3, 1st para
The 'sip.app-subtype' media feature tag is of type token with a case-
insensitive equality relationship. Its value can be any registered
| or private MIME application subtype compliant to the subtype-name
grammar defined in [RFC4288]. [...]
[[ see also subsequent errata note covering another issue as well ! ]]
d) Section 3, 3rd para
It is important to note that this media feature tag is only
indicating the streaming media types that a user agent is capable of
supporting. It says nothing about the functionality provided by the
| user agent itself or the MIME types that the agent can send or
receive in SIP messages or emails. For example, let us assume that a
SIP user agent is capable of supporting a chess game. The game is
played by each user sending chess moves as binary objects over UDP
| between a pair of user agents. Those objects have a MIME type of
"application/example". [...]
e) Section 3, 4th para
A consequence of this is that, as new streaming media type formats
are defined (such as game stream formats, whiteboard session formats,
and so on), they SHOULD be defined using the SDP application stream
| and utilize a MIME application subtype.
f) Section 6, 4th para
Summary of the media feature indicated by this tag: This feature tag
| indicates the MIME application subtypes supported by the agent for
purposes of streaming media.
It should say:
a)
A Session Initiation Protocol (SIP) Media Feature Tag for
'Application' Media Subtypes
b)
The caller preferences specification for the Session Initiation
Protocol (SIP) allows a caller to express preferences that the call
be routed to a User Agent (UA) with particular capabilities.
Similarly, a specification exists to allow a UA to indicate its
capabilities in a registration. Amongst those capabilities are the
| type of media streams the agent supports, described as top-level media
| types. The 'application' media type is used to describe a broad range
of stream types, and it provides insufficient granularity as a
capability. This specification allows a UA to indicate which
application subtypes the agent supports.
c)
The 'sip.app-subtype' media feature tag is of type token with a case-
insensitive equality relationship. Its value can be any registered
| or private 'application' media subtype compliant to the subtype-name
grammar defined in [RFC4288]. [...]
d)
It is important to note that this media feature tag is only
indicating the streaming media types that a user agent is capable of
supporting. It says nothing about the functionality provided by the
| user agent itself or the media types that the agent can send or
receive in SIP messages or emails. For example, let us assume that a
SIP user agent is capable of supporting a chess game. The game is
played by each user sending chess moves as binary objects over UDP
| between a pair of user agents. Those objects have a media type of
"application/example". [...]
e)
A consequence of this is that, as new streaming media type formats
are defined (such as game stream formats, whiteboard session formats,
and so on), they SHOULD be defined using the SDP application stream
| and utilize an 'application' media subtype.
f)
Summary of the media feature indicated by this tag: This feature tag
| indicates the 'application' media subtypes supported by the agent
for purposes of streaming media.
Notes:
Rationale:
The subject of the RFC is SIP, not e-Mail, the 3rd letter in "MIME".
Therefore, the RFC should better follow the explanations given in
RFC 4288, which places the original concepts from MIME that have
proven generally useful into a more general context and strongly
recommends talking about "media types" and "media subtypes".
That reasoning similarly holds for Media Features, which for
obvious reasons not have been denoted "MIME Features".