Hi,
We have never been asked for suck characteristic of the magnetometer, unfortunately it is not characterized, or at least not with this same name.
The characterized information we have for the magnetometer of the FXOS8700 is the Zero-flux offset accuracy which I think is the data you are requesting for.
For the FXOS8700 the Zero-flux offset accuracy is set to +/-10uT.
The zero-flux offset describes the deviation of the output signals from zero when the device is shielded from external magnetic field sources (that is, inside a zero-Gauss chamber).
Regards,
Jose