Difference between resolution and precision

Hi,

  Reading the specification of graphics tablets, I've found that they give
resolution (in dpi) and precision.

  For a graphire, resolution is 1000 dpi (wich woulds mean 5000*4000
different position one the tablettes), but precision is 0,5mm (wich would
mean 256*205 position !!)

  Can you give me the meaning of this parameter for a pen tablet ? (I
understand what DPI are for a scanner, printer, screen, but here the fact
that they give DPI + precision confuse me)

Regards,
Fabien.