Interoperability is primarily a matter of the use case, not of the technology. Policymakers considering interoperability mandates need to be watchful for extremes of perfection or compromise, which both offer a game to be exploited by the unscrupulous.

Reviewers of a paper concerning interoperability complained that some sections seemed to imply only 100% functional equivalence would be acceptable, and told us “much smaller percentages are perfectly adequate.” So how much interoperability is enough interoperability? The answer, dear to the hearts of every politician, is “it depends”.