MIME subclasses

David Faure dfaure at trolltech.com
Wed Oct 1 00:34:50 EEST 2003

On Tuesday 30 September 2003 21:12, Jonathan Blandford wrote:
> Thomas Leonard <tal00r at ecs.soton.ac.uk> writes:
> > While thinking about the syntax for subclassing MIME types
> > (application/x-python > text/plain > application/octet-stream) some more,
> > it occurred to me that a syntax already exists for this.
> Did I miss a discussion on adding additional subclassing to MIME Types?
> They already have a natural inheritance.  For example, text/plain is
> already text, and image/gif is also an image.  The fact that people
> rarely use this information leads me to think that this subclassing is a
> bad fit.  I don't see what saying that text/plain is also
> application/octet-stream actually buys us?  What is the problem we're
> solving here?

As I said previously: mimetype inheritance is needed, with a much more 
flexible model than "image/gif is an image".

- many mimetypes are actually specializations of text/plain
 (and not all are called text/*. For instance application/x-perl etc.)

- OpenOffice files and KOffice files are specializations of application/x-zip
(this allows to offer a zip utility for office documents)

- (implicitely) all mimetypes except inode/* are specializations of application/octet-stream
(saying this allows to bind them all to an hex editor at the bottom of the offers list)

- text/xml is a specialization of SGML (if sgml tools apply to xml)
- text/docbook is a specialization of XML (yes, I know that text/docbook is not the
standard name, but you get the idea)
etc. etc.

I'm sorry, but if the XDG spec doesn't allow KDE to model mimetype inheritance,
I don't see how KDE could switch to it at some point. This is something we
already model and use, so we definitely need it in whichever replacement we
adopt. If other apps/environments ignore the inheritance, it shouldn't be a big

This being said, I'm not a bit surprised by the RDF idea - but I know little
about RDF.

David FAURE, faure at kde.org, sponsored by Trolltech to work on KDE,
Konqueror (http://www.konqueror.org), and KOffice (http://www.koffice.org).

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