[postgis-users] Different srtext for the same SRID ?

[Arnaud Lesauvage]

Hi list !

I have received some shapefiles containing data in UTM31N 
coordinates-system (SRID=32631).
The data came with a .prj file (one for each set of .shp and .dbf) 
containing a PROJCS string.
This string differs in some ways with the one in my 
spatial_ref_sys table, and I was wondering whether I had to worry 
about that or not.

Here is the one from my dataset :
PROJCS["UTM-31N",
GEOGCS["WGS84",
DATUM["WGS84",SPHEROID["WGS84",6378137.000000,298.257224]],
PRIMEM["Greenwich",0.0],
UNIT["Degree",0.0174532925199433]],
PROJECTION["Transverse_Mercator"],
PARAMETER["False_Easting",500000.0000000000],
PARAMETER["False_Northing",0.0000000000],
PARAMETER["Central_Meridian",3.0000000000],
PARAMETER["Latitude_Of_Origin",0.0000000000],
PARAMETER["K0",0.999600],
UNIT["Non-Meter",1.000000]]

And the one from PostGIS (I removed the "AUTHORITY" strings for 
better readability) :
PROJCS["WGS 84 / UTM zone 31N",
GEOGCS["WGS 84",
DATUM["WGS_1984",SPHEROID["WGS 84",6378137,298.257223563]],
PRIMEM["Greenwich",0],
UNIT["degree",0.01745329251994328]],
PROJECTION["Transverse_Mercator"],
PARAMETER["latitude_of_origin",0],
PARAMETER["central_meridian",3],
PARAMETER["scale_factor",0.9996],
PARAMETER["false_easting",500000],
PARAMETER["false_northing",0],
UNIT["metre",1]]

There are two ovious differences : the PostGIS version has a scale 
factor whereas the .prf file has a "KO" property with the same 
value. I don't know what this means, but does it matter ?
Second difference is that the .prj file says that the unit is 
"non-meter", whereas PostGIS says that it is "metre" (="meter" in 
French).

Does any of this difference have some kind of importance ?

Thanks a lot for your help !

Regards
--
Arnaud