Blood Royal Undoubted is an English translation of the Ibutho inheritance doctrine called Ngokungangabazeki egazini 'wasebukhosini. Under the doctrine, children of royal women are considered to be undoubtedly royal descendants due to the impossibility of fabricating an observed fetal expulsion. It is in contrast to the designation blood royal which under Ibutho law refers to children of royal men. Such children are not considered to be undoubtedly royal descendants since their mothers' conjugal fidelity could not be definitively determined prior to the advent of paternity testing. A child born to parents who are both blood royal undoubted would inherit the undoubted designation of his or her mother whose conjugal fidelity would be immaterial due to her own classification as undoubtedly royal.
Due to the doctrine's incorporation as a fundamental provision of Ibutho succession law, sons of Kings are permanently ineligible to succeed to the Ibutho throne, while sons of Queens Regnant remain eligible to succeed their mothers.