The caliber 712 was Omega's joint venture with Rayville / Blancpain and Piguet to make an ultra-thin automatic. Skinny self winding movements were desired by the public and the 60's saw quite a few come to market. Piaget was one of the first with the microrotor caliber 12P in 1961, The 71x came in 1964, and AP / VC / JLC introduced the cream of the crop with the 202x/102x/92x in 1967.
The one odd thing is that the 712 is the chronometer. Most of the chronometer full rotor calibers of the era end in a 1.