ADXL375 offset register/Shock Threshold

1. I have to write offset register values in adxl375.
On putting device so that x = 0g , y = 0g & z = 1g
I get output valuesfrom adxl375 as; xreg = -14 , yreg = 15 & zreg = +34


Now what should I write to offset registers of adxl375;
a). Is it invert of each value

b). I read AN-1077 describing offset regsiter value of adxl345, it had mention values as
X_CALIB = –(OUTPUT (X) ÷ 4)
Y_CALIB = –(OUTPUT (Y) ÷ 4)
Z_CALIB = –((OUTPUT (Z) – 256) ÷ 4)

c). which of above I should choose







2. I had to enable double/single threshold interrupt.
I had read that this register is 780mg/LSB.

Also datasheet says:
"The SHOCK_AXES register specifies the participation of each of the three axes in single shock/double shock detection."

How does it correlates to values in THRESH_SHOCK register.
Is it
THRESH_SHOCK = sqrt( (dataX * dataX) + (dataX * dataX) + (dataZ * dataZ) )