[uf-new] Separating File Content from File Format
msporny at digitalbazaar.com
Fri Apr 6 09:27:01 PDT 2007
Charles Iliya Krempeaux wrote:
>> Hmm, reading that gives me the impression that parameters are defined
>> when media types are registered, and aren't something we can add to
>> suit our needs.
> I don't believe that is the case.
> I believe (according to the spec) you are free to create your own
> Content Type parameters.
I disagree, you could break backwards compatibility if you start tacking
on parameters that are not defined in the MIME-type (which is used in
the Accept and Content-Type fields):
"When sending data to older HTTP applications, implementations SHOULD
only use media type parameters when they are required by that
I can't find any statement in the literature that says that you can add
parameters that are not in the "Required" or "Optional" listing.
Furthermore, RFC 2045 states:
"Use of non-registered media types is discouraged." 
"MIME implementations must ignore any parameters whose names they do not
I believe this means that web browsers should ignore any parameters
whose names they do not recognize. That means if it isn't in the
MIME-Type specification, it should be ignored by any implementation
reading a field containing the MIME-Type.
In short - if it isn't registered with the Mime-Type - you shouldn't be
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