[DotGNU]pnetlib platform dep?

[S11001001]

The System.Uri.LocalPath (or something like that) spec says that it should 
create a platform-specific path, using its characters, etc. So

file:///usr/local/bin/ilrun

becomes
/usr/local/bin/ilrun
on GNU,
usr:local:bin:ilrun
on Mac,
c:\usr\local\bin\ilrun
on Windows (actually, not sure about that one)

so my question is about things that are platform-specific, but not implying 
that their specificity requires internal impl. So should I stick a 
[MethodImpl(MethodImplOptions.InternalCall)] on it, or what?

--
We should start referring to processes which run in the background by their
correct technical name... paenguins.
        -- Kevin M. Bealer, commenting on the penguin Linux logo