Thanks to all. Now I' ll be trying again and again two of the variants.

But I haven't heard yet the answer to another question - precision, is there a number 
position that is insignificant. Phrase "If those coord are meters, you want a 
precision to the tenth of a millimeter" looks like this, but I have coordinates in 
meters and error appears in 0.0001m = 0.1 mm.

And how could I change coordsys in MapX except NumericCoordsys and DisplayCoordsys. 
These bounds do not change a table, available only at runtime.

 

Hi Kat

MapInfo stores coordinates as a whole number ( 4 byte integer ) times a
step size ( 8 byte double precision ).

The X step size is ( Max X - Min X ) / 2,000,000,000

The Y step size is ( Max Y - Min Y ) / 2,000,000,000


It therefore does not follow that smaller bounds mean more accuracy. If
all your coordinates are in exact multiples of 1 mm it is better to have
a step size of 1 mm than say 0.75 mm. With 0.75 mm units would fall at
0.75, 1.5, 2.25, 3 so 2mm could not be represented whereas it could with
1 mm step.

To set an exact step size make your bounds 2,000,000,000 times the step
size you want.

For the UK we set our bounds to 2000 km which gives us a step size of
exactly 1 mm. As Ordnance Survey give out coordinates for MasterMap to
the mm this means we can store and retrieve coordinates "Spot on".

Regards


Bob
mapsbydesign.co.uk



Best Regards,
Katerinka

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