Method for calculating Elastic Modulus

Please describe the method used to calculate the elastic modulus. The closest I could find is slide 13 in the user guide, but I'd like to know:

- Is the origin a fixed point (0,0) in the curve fit? Or is only the simulated data used to fit a straight line?

- What region of the stress-strain curve is included in the calculation- up to a certain % strain? If so, what %? Some of the stress strain curves are more non-linear than the example shown, so knowing this detail will be helpful.