The 123\CITROEN-DV-4-R (also known as 123\DV-R) is essentially the same unit as the 123\DS-A or the 123\DS-R : it contains the same set of 16 advance-curves.
Might you require vacuum-advance : specify a ‘123\CITROEN-DV-4-R-V’.
The difference is its shape to fit certain “DV” engines, as Citroen produced in 1966 and 1967. This can easily be seen, by the two M7 – bolts sticking out of the engine, for mounting the distributor. This explains the different shape of this 123-ignition.