Nsgarch:
I don't work within the EU, so I cannot claim to know the DIN data books inside and out. But I do work with a company who manufactures the actual tonearm connectors (and supplies various tonearm and cable manufacturers with same). Absolutely no mention of "DIN" from these guys. None. From the DIN connector books that I have looked at personally, the tonearm connector does not appear to be covered under DIN. Ditto also for the JIS books.
Now if anyone knows of the specification number for this connector under either the JIS or DIN system, I'd be happy to check it out and verify it.
There is a certain DIN connector specification which if modified, will give you something fairly close to the tonearm connector. I reckon that it is possible that the design of the tonearm connector was partly derived from this DIN connector. But if I recall correctly, although there were similarities, there were also non-trivial differences.
As far as I have seen, the tonearm connector has been in use in tonearms from at least the mid 70s, and may be even older. I have an original FR-64s (an Ikeda design) which has this connector.
BTW, SME does buy some of its componentry from Japan - I thought that they used Ito (who produced the Ittok for Linn). SME could be making the connector themselves, or sourcing it from somewhere in Europe, but it could also be from Japan.
As for challenging people on anything, one has to consider whether it is worth the effort, especially since if it is of no direct benefit to you. And in my case, given the same amount of time and effort, I could certainly be doing other, far more interesting and productive things, like design and development. Beyond a certain point, arguing is a waste of time and boring.
And pragmatically, as long as you're not involved in manufacturing the tonearm connectors or incorporating them into your own arm design, and you (and the people that you talk to) know what kind of thing the DIN / tonearm connector is, maybe that's sufficient.
regards, jonathan carr