B210 Sleeper
Here in Australia, our Datsuns all came with a manufacturers ID plate, same as everywhere else, but after a certain date, around 1974 I think, all the states had agreed on a number of "Design Rules" that were to be uniform across the whole country. These were known as "Australian Design Rules" or ADR's for short.

Each category had a number assigned to it & for smog equipment it was ADR27. As each additional specification was introduced, the number got a suffix. I'm pretty sure that my 1980 car is certified to comply with ADR27A & a year or two later it would need to be ADR27B. You get the picture.

The vehicle manufacturer needed to affix a plate to each vehicle that stated that the vehicle, whose chassis number & other relevant data was stamped on it was built [engine & chassis were joined] on the date that was also stamped on the plate [month & year only] This plate went on to declare that the vehicle complied with the following ADR's, then went on to list the relevant numbers with which it complied.

This satisfied the registration Nazi's & all was well with the world, however, there are some among us that sometimes confuse this 'compliance plate' with the makers ID plate & also confuse the 'car number' or 'chassis number' with a V.I.N. which was not introduced into this country untill the late 80's I think.
[A V.I.N. is a 17 character ID that is internationally recognised & in it is encoded the country of manufacture & the manufacturers code ID as well as other relevant information. It replaces the former chassis number as a form of vehicle ID.]

So there you go, a compliance plate simply declares that the vehicle was made in a certain month & year, is stamped with the chassis number or V.I.N. [as appropriate] & the list of relevant ADR's that it complies with. Various makers also included other details as well, so a compliance plate is unique to each vehicle because of the chassis No. or V.I.N. stamped into it.
These plates were affixed in addition to the makers plate, not 'instead of' the makers plate.