[OpenLayers-Users] Is it possible to completely change the projection of a Map?

[Nick Whitelegg]

On Monday 07 May 2007 12:24, you wrote:
> On Mon, May 07, 2007 at 12:01:47PM +0100, Nick Whitelegg wrote:
> > Hello everyone,
> >
> > As part of an OpenStreetMap editing application I'm doing, I would like
> > to be able to replace not only the layers but also the projection of the
> > base map. The application is a point-of-interest editor for
> > OpenStreetMap, it allows users to use the OpenLayers Vector layer to
> > trace the outlines of lakes and woods and also add POIs like hill
> > summits. I want users to be able to switch between two base layers.
> >
> > The two base layers comprise Freemap (OpenStreetMap rendering client)
> > which is projected in Mercator, and the New Popular Edition (old Ordnance
> > Survey maps of the UK) which has the OSGB36 projection.
>
> Add the projection properties to each layer. Layers inherit their
> projection from the map, but if they're different, then when you switch
> layers, the projection will change.

OK thanks. 
Can I explicitly state a projection and it'll handle converting the units for 
me?  How do I state that it's OSGB or Mercator projection?

Thanks,
Nick