protocol/scheme entry in .desktop?

[Jakob Petsovits]

On Monday, 26. November 2007, Patrice Dumas wrote:
> Currently the mime information that allows to chose an application based
> on the mimetypes it handles is part of the .desktop file. But another
> item of an url that could be a criterium for application selection is the
> protocol/scheme that appears in front of urls, like http, ftp or file.
> So maybe it could be nice to add a new entry in the desktop entry,
> called Protocol or Scheme, with a ; delimited list of protocols handled
> by the application.
>
> This solves a real use case (well, in my opinion), taking pdf as an
> example, evince handle http url while xpdf doesn't, still evince isn't
> a generic browser (like firefox, for example). So this seems to me
> to be an interesting application property to exhibit.

What if this is not an application property at all?
In KDE, network transparency is provided by kioslaves, and you can extend or 
shrink the range of those just by installing or uninstalling kio plugins.

I would guess this doesn't map too well to a predefined set of protocols?