The document discusses documents for which registration is optional under Indian law. It notes that Section 17 and 18 of the Registration Act specify documents that must and may be registered. Documents that do not need to be registered include wills, powers of attorney, agreements to sell, agreements for partition, tenancy agreements under one year, promissory notes, agreements of mortgage, deeds of adoption, simple contracts, and releases. While not required, parties have the option to register such documents, though failure to register does not invalidate them or affect their admissibility as evidence.