OK thanks for this !
So one final question related to importing shapefiles that follows from your last point....
I have a shapefile that uses the following projection details (taken from the .prj file):
PROJCS["ED_1950_UTM_Zone_30N",GEOGCS["GCS_European_1950",DATUM["D_European_1950",SPHEROID["International_1924",6378388.0,297.0]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Transverse_Mercator"],PARAMETER["False_Easting",500000.0],PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian",-3.0],PARAMETER["Scale_Factor",0.9996],PARAMETER["Latitude_Of_Origin",0.0],UNIT["Meter",1.0]]
If I import this shapefile into an existing Explorer on-line file with the Bing Basemap pre-loaded do you know which "default transformation" will be used ? I want to know basically whether this will produce an accurate result or not. The file I am working on covers southern France and northern Spain.
thanks again for your help.
Jonathan