The term "capital" as used in this title embraces the amount of outstanding capital notes and debentures legally issued by any banking institution. The capital stock of a banking institution is unimpaired when the amount of such capital notes and debentures as represented by sound assets exceeds the impairment as found by the commissioner. The commissioner must approve of any retirement of any capital notes or debentures and may require the bank to issue some other form of capital before retiring the capital notes or debentures.
N.D.C.C. § 6-03-42