Re: Notation System IDs

At 4:55 PM +0000 4/4/97, Christopher R. Maden wrote:

>Clause 4.6: I *strongly* feel that MIME types should be allowed for
>notation system IDs.  Unless someone can send me a URL for a GIF
>processor that will work immediately on any OS.  Change %ExternalID in
>production [73] to %NotExtId, which in turn is:
>   [73a] NotExtId :: = 'SYSTEM' S (MimeType | SystemLiteral)
>In more detail, I've always thought that the identifiers for notations
>were a little weird.  In a fixed environment, it's fine to put, say,
>"xv" as the system identifier for GIF.  But in a language defined
>primarily to enable Internet transfer, this makes NO sense.  URLs are
>great because they work (or don't) everywhere on the 'net.  But URLs
>for notations point to - what?  A specification of the notation?
>That's useful, and good luck finding a URL describing the binary
>structure of proprietary formats.  A MIME type, registered or
>unregistered, seems much more appropriate for Internet use for
>What do other folks think?

You're right. There is a problem of notations that are not registered
Mime-types, but they are not likely to interoperate well, anyway.

Maybe we could _allow_ URLs instead of Mime-types (the : after the scheme
name would disambiguate, no?) -- If and _only if_ there is no Mime-type
available for a data format.

Insofar as the notation labelling problem has been solved _anywhere_ Mime
types are the solution.

   I will be _very_ surprised if anyone can find an argument _for_ URLs
referencing some unknown resource, rather than a Mime-type -- especially
when we are explicitly targeting the Web and HTTP.

   -- David

Note: now that we have PUBLIC, we could state that PULBIC IDs for notations
are Mime types and leave the SYSTEM ID as the one that is not well-defined
as to semantics....

Seems an ironic reversal of the other case, but this is a place where the
Naming probelm is better solved than the resolution problem.

David Durand              dgd@cs.bu.edu  \  david@dynamicDiagrams.com
Boston University Computer Science        \  Sr. Analyst
http://www.cs.bu.edu/students/grads/dgd/   \  Dynamic Diagrams
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