The software determines the data used to construct the arc as follows:
First, the software determines a segment of the scan using a starting point and an ending point within the scan. The software chooses the starting and ending points as the point in the scan nearest [start_x, start_y, start_z] and the point nearest [end_x, end_y, end_z] respectively.
The software then discards the points from the start and end points of the scan. The number of points discarded from the start is discard_start and from the end is discard_end. An arc is then fitted to this set of points.
Finally, the software adds the starting and ending points back in if they are within the defined tolerance. The arc is then re-fitted once more to the new set of points.
The value of fit_type may be BF (Best Fit) or BFRE (Best Fit Recompensate). This determines whether the software performs a best fit or best fit with recompensation when calculating the arc. For a description of Best Fit and Best Fit Recompensate, see "Constructing a Best Fit or Best Fit Recompensate Circle".