2.1.897 Part 1 Section 18.17.7.37, CHIINV

a.   The standard specifies that an iterative search technique is used for the implementation of the CHIINV function.

Office does not require an iterative search technique to be used.

b.   The standard lists #N/A as the return value in case the search has not converged after some number of iterations.

Office does not require an iterative search technique to be used.