Well, i've never used theese modern ones with integrated coils. I've only used the KMZ10 without the coils. Had to wind them myself which was a major pain in the ......

It all goes like this. The Set/Reset(aka flip) coil is used to invert(flip) the output of the sensor. This is very handy when doing measurements since you can use this to measure the offset of your analog system(sensor + amplifier). If you get a signal of 3.5 volts in one measurement and you get 1.5 volt when flipped, you can calculate the zeropint as (3.5+1.5)/2=2.5volts. The signal itself is ofcourse 3.5-2.5=1, or 1.5-2.5=-1 if you're in the flipped state. This coil is also used to "reset" the sensor if it has been exposed to a VERY powerful magnetic field which would otherwise mess up the output.

The compensationcoil is used to move the offset point. It adds(or subtracts) to the measured field.

If my memory serves me right Philips had an appnote on how to build a compass with theese sensors. Go look.

/Ingvar