Registration request for MIME media type tag 3gpp-ims+xml

Bjoern Hoehrmann derhoermi at
Tue Jul 8 12:50:09 CEST 2008

* John M Meredith wrote:
>> "sv" or "schemaversion" the parameter's value is used to indicate:
>>  - the versions of the 3GPP IM CN Subsystem XML schema that can be
>>    used to validate the 3GPP IM CN subsystem XML body (if the MIME
>>    type and parameter are present in the Content-Type header) or
>>  - the accepted versions of the 3GPP IM CN Subsystem XML body (if the
>>    MIME type and parameter are present in the Accept header).
>> If the "sv" or "schemaversion" parameter is absent, it shall be
>>    assumed that version 1 of the XML Schema for the IM CN subsystem
>>    XML body is supported.

I am a bit confused by the use of "or" here, it sounds as if the naming
of the parameter is unclear; perhaps it would be better to use "and". If
the intent is to say that one may use one or the other, but not both at
the same time, that should be said explicitly.

Do I understand the first paragraph correctly, that the legal syntax and
semantics of the parameters varies depending on the context where type
and parameters are specified? If so, are there other registered types
that have similar parameters?

>> This registration entry includes ABNF that modifies the m-parameter
>>    definition in RFC 3261 [26].  m-parameter allows for
>>    attribute/value pairs that are applicable to the media range. In
>>    particular, the ABNF below is given for a media range
>>    application/3gpp-ims+xml specific m-parameter.
>> m-parameter    /= ("sv" / "schemaversion") EQUAL LDQUOT [ sv-value-
>>    list ] RDQUOT
>> sv-value-list  =  sv-value-range *( "," sv-value ) sv-value-range =  
>> sv-value [ "-" sv-value ]
>> sv-value       =  number / token
>> number         =  1*DIGIT [ "." 1*DIGIT ]

It seems incorrect to me to modify other specification's productions in
a media type registration. Is the idea here simply to specify the legal
syntax for the parameters? If so, it would be much better to just say
what the legal parameter values are, and leave the rest to other speci-
fications, so just something like

  sv-parameter-value = sv-value-list

Permissable quote marks, placement of optional white space, and similar
things as they are specified in the m-parameter production, are subject
to higher level protocol specifications, and I believe existing ones do
vary in how they encode the parameters and their values.
Björn Höhrmann · mailto:bjoern at ·
Weinh. Str. 22 · Telefon: +49(0)621/4309674 ·
68309 Mannheim · PGP Pub. KeyID: 0xA4357E78 · 

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