[Proj] Swiss Grid Systems

[Paul Kelly]

On Sun, 12 Jul 2009, Irwin Scollar wrote:

> Swiss Grid Systems
>
> May I suggest that interested participants in this discussion thread open:
>
> http://www.swisstopo.admin.ch/internet/swisstopo/en/home/apps/calc.html

Thanks, that was quite helpful. It also led me to the discovery that 
exactly the same thing was being discussed on *this* list just under 8 
years ago:
<http://lists.maptools.org/pipermail/proj/2001-September/000248.html>

In summary, all the sources seem to suggest that the old 7-parameter 
transformation given in the Grids & Datums column was simply inaccurate 
and has been recalculated more accurately since it was originally 
publicised. I'm still curious as to the subtle difference between the 
3-parameter transformation given in the column and that that is now 
generally accepted, but in my mind anyway things are a lot clearer - 
thanks.

Paul