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The transition from ONIX 2.1 to 3.0 isn't actually that difficult, but if you haven't changed anything in your metadata when you make it, then there's two possible reasons: You support a superb and very complete set of ONIX 2.1 metadata elements – and you should work to understand how much better and more precise that data can be in ONIX 3.0; OR you've taken a not very full ONIX 2.1 and made it into a very incomplete ONIX 3.0 file. ONIX 3.0 is intended to fix supply change chain problems that have come up since ONIX 2.1 was created. It supports a higher level of accuracy and ONIX 3.0 users expect to be able to find it.
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