[Proj] towgs84 values for EPSG:27700

Hermann Peifer peifer at gmx.eu
Mon Feb 20 14:25:37 EST 2012

On 20/02/2012 10:45, Mikael Rittri wrote:
>> Is this expected behaviour?
> I can say that I, for one, didn't expect it. Because as far as I know,
> the default datum shifts in both Proj.4 and GDAL/OGR come from the
> gcs.csv file that is part of libgeotiff.
> However, the gcs.csv file is changed now and then. The default datum
> shift of OSGB 1936 was changed from the 7-parameter (epsg:1314) to the
> 3-parameter (epsg:1195) in the libgeotiff changeset 2023, of May 23, 2011.
> The changeset message was just "upgrade to EPSG 7.6 database".
> http://trac.osgeo.org/geotiff/changeset/2023/trunk/libgeotiff/csv/gcs.csv

Thanks for the hint, I should have known. I keep forgetting that there 
is a variety of gcs.csv and pcs.csv files around: as part of libgeotiff, 
GDAL/OGR and GRASS, plus the epsg file which comes with PROJ. I have to 
pay more attention to keeping them in sync.


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