The base movement was designed by JLC (caliber 920) and used by the whole holy trinity: Patek Philippe (e.g. in the Nautilus 3700), AP (e.g. in the 15202) and VC (e.g. in the Traditionelle line)
Also both AP and VC used it as a base movement for many of their complications. This movement was the base for many references of AP and VC. Such as their perpetual calendars, equation of time and world times. But looks like AP will retire this movement w...