Subject: media type?

From: "Jeroen Bekaert" <[email-masked]>
Date: Thu, 27 Nov 2003 18:32:50 -0700

Dear all,

I the context of some research I am conducting at the Los Alamos National
Laboratory, I encountered the following ambiguity regarding the meaning of
'media type'.

Assume I have a parameter called Y. Y is defined as follows:
"Y = a MIME media type value indicating the type of a resource". According
to both RFC 2045 and 2046, the exact meaning of Y could be defined as one of
both:

- According to RFC 2045, a media type is:
"The purpose of the Content-Type field is to describe the data contained in
the body fully enough that the receiving user agent can pick an appropriate
agent or mechanism to present the data to the user, or otherwise deal with
the data in an appropriate manner. The value in this field is called a media
type."

As such, a possible value of Y could be "text/xml; charset=utf-8"?

- Based on some illustrative examples in RFC 2046, I could also derive that
a media type is a general category of data content, such as: 'application',
an 'image', a 'text' message, a 'video' stream, and so forth. Each of these
media types can have 'subtypes'. For example, the 'text' media type has four
subtypes: 'plain', 'richtext', 'enriched', and 'tab-separated' values.

As such, a possible value of Y could be: "text"

Am I correct in stating this? Could someone clarify this ambiguity? How
should I change the definition of Y in order to exclude one of both
meanings?

Thanks in advance
Kind regards
Jeroen Bekaert

--
Digital Library Research and Prototyping team
Los Alamos National Laboratory
PO Box 1663, MS P362
Los Alamos, NM, 87545, USA
tel. +1 (505) 664 0580

Department of Electronics and Information Systems
Faculty of Engineering, Ghent University
Sint-Pietersnieuwstraat 41
B-9000 Ghent, Belgium

---

From: [email-masked]
Date: Thu, 27 Nov 2003 22:34:00 -0500

> As such, a possible value of Y could be: "text"

You want media-type to be "text" with a  subtype of "xml" and
a parameter "charset=utf-8".

I don't see any way to use the BNF of RFC2046, section 5.1 to get any
other parse.  In fact, further down in section 5, it says:

   type of data.  Thus, a media type of "image/xyz" is enough to tell a
   user agent that the data is an image, even if the user agent has no
   knowledge of the specific image format "xyz".  Such information can
   be used, for example, to decide whether or not to show a user the raw
   data from an unrecognized subtype -- such an action might be
   reasonable for unrecognized subtypes of text, but not for
   unrecognized subtypes of image or audio.  For this reason, registered

So the intent is to have the media-type say "this is text" or "this is an
image" or "this is a sound" or "this is a composite", and so on, so that an MUA
can make a vague guess as to what do with it even if it has no clue at all what
to do with the specific subtype or parameters. For instance, an MUA would be
within it's rights to refused to deal with *any* flavor of text/* (including
even text/plain) if it included a 'charset=' parameter it didn't know how to
deal with.  As an example, displaying *any* sort of Big5 text on a display that
is ascii/8859-* only is basically doomed...

---

From: "Jeroen Bekaert" <[email-masked]>
Date: Thu, 27 Nov 2003 21:36:37 -0700

Dear Valdis,

Thanks for your reply! If I understand this correctly, defining Y as:

1. "a MIME media type value indicating the type of a resource" results in:
"text"

2. "a concatenation of MIME media-type, subtype and parameters indicating
the type of a resource" results in: "text/xml; charset=utf-8"

3. "a MIME content-type value indicating the type of a resource" results in:
"Content-Type: text/xml; charset=utf-8"

Regards
Jeroen Bekaert

> -----Original Message-----
> From: [email-masked] [mailto:[email-masked]] On Behalf Of
> [email-masked]
> Sent: Thursday, November 27, 2003 8:34 PM
> To: Jeroen Bekaert
> Cc: [email-masked]
> Subject: Re: media type?
>