[IanCal]

I think that's addressing a different problem. There are two distinct issues:

1. Is the data correct?

2. Has the data been changed?

For many cases, 1) is not solvable in software.

I'm not sure I really understand why 2. is something best solved with a blockchain with a private group, but given people who have actually looked into this when I haven't think it's relevant means I'm probably missing something either on the requirements, difficulty to implement or features.

[hnarn]

You're correct that #1 isn't solvable in software, but I have doubts that #2 is best solved with a blockchain.