For background, see the original post. Use whatever estimation units you prefer – days, story points etc.

The v and vv fields will be calculated from the historical velocities hv if these are provided.

Example: ni = 10 (iterations), v = 20 (story points per iteration), rc = 2 (story points per iteration), vv = 20 (percent) suggests those 10 iterations should include a contingency element of 1.5 iterations (or 27.8 story points at the effective velocity), allowing 152.2 story points of critical work to be attempted with 95% confidence.