2. Phra Ong Chao -- there are two specific grades within this rank, those Phra Ong Chao who have the additional word Chao within the preamble to their title, and those who do not : [Phra Chao Vorawongse Ther] Phra Ong Chao--Prince or Princess and Royal Highness. [Phra Vorawongse Ther] Phra Ong Chao--Prince or Princess and Highness. The Phra Ong Chao nowadays are always the grandchildren of a king -- three of the present King's grandchilden are of this rank, and the other 10 living Phra Ong Chao are all grandchildren of King Chulalongkorn [ Rama V ], from senior lines of descent.