Question on shared-mime-info adoption

[Luca Dionisi]

> That is, when it finds the mime-type of a file (following the
> shared-mime-info), then:
>  -  does it try to find the iconname following the Desktop Entry spec.?
>  -  does it try to find the icon file following the Icon Theme spec.?
>
> There is a dir, /usr/share/themes, that I don't understand the meaning of.

Little update.
I found by myself that /usr/share/themes is (well, I presume)
used for the styles of the widgets and the windows.

But my questions are still valid:

Which "route" does Nautilus follow to find the icons for a file?

Luca