[GRASS5] m.proj Difference?

[Markus Neteler]

On Fri, Jun 07, 2002 at 12:43:26PM +0100, Glynn Clements wrote:
> 
> Jeshua Lacock wrote:
> 
> > I entered all of the same projection values as I did before, and when I 
> > attempt to convert the same values I converted with Beta 11, I get 
> > results in the Y within 0.7 meters, and the X is off by about 510 
> > meters. I get similar results with adjacent coordinates being off by a 
> > slight amount positively or negatively based on the direction traversed 
> > from the first test point.
> > 
> > All of the coordinates that I converted with Beta 11 are on the money, 
> > and I need to convert some more because of a data loss.
> > 
> > It seems like it must be a datum shift or some slight difference in the 
> > ellipsoid parameters.
> 
> Unlike earlier versions, the pre4 version of the proj library performs
> datum shifts. Ensure that both locations have the correct datum.

Am I right that datum shifts are only performed between NAD27 and NAD83
but not for, say, European datums?

Markus