Okla. Stat. tit. 58, § 1256

Effect of deed on joint tenancy - “Joint owner” defined. A. A record joint owner of an interest in real estate may use the procedures in the Nontestamentary Transfer of Property Act to title the interest in transfer-on-death form. However, title to the interest shall vest in the designated grantee beneficiary or beneficiaries only if the record joint owner is the last to die of all of the record joint owners of the interest. A deed in transfer- on-death form shall not sever a joint tenancy. B. As used in this section, "joint owner" means a person who owns an interest in real estate as a joint tenant with right of survivorship.