[Talk-GB] Calling all projection experts: WGS84 parameters

[Steve]

Hello fellow OSMers

A hopefully straightforward newbie question for you...

I'm currently uploading various new polygons via shapefiles created in 
Quantum GIS.  These use the WGS84 (EPSG:4326) projection, which Quantum 
defines as:

+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs +towgs84=0,0,0

A fellow mapper is doing similar, great stuff mapping administrative 
boundaries (Parishes etc) from Ordnance Survey, and setting the 
projection with the following parameters:

+proj=longlat +ellps=WGS84 +datum=WGS84 +zone=30 +no_defs

Because of the different parameters (i.e.  I have +towgs84=0,0,0, and he 
has +zone=30), there is a slight offset in data we are creating in the 
same areas.

The question is: which one of us is correct?

Thanks for your help

Steve Peters (aka SemanticTourist)

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