IIRC Unicode doesn't define country codes. It was a workaround for a political issue of which countries recognize which other countries.

It would have been difficult to get the CN delegation to sign off on a list that contained TW, although there are probably others.

There are many more than I realised - Wikipedia has a decent list https://en.m.wikipedia.org/wiki/List_of_states_with_limited_...

As I understand it, there is no two-letter ISO code for the USSR because when they update the standard they remove countries that no longer exist. In at least one case they have reused a code point: CS has been both "Czechoslovakia" and "Serbia and Montenegro", neither of which currently exist.

As a result, two-letter ISO codes are useless for many potential applications, such as, for example, recording which country a book was published in, unless you supplement them with a reference to a particular version of the standard.

Is there a way of getting the Czechoslovakian flag as an emoji? And did Serbia and Montenegro get round to making a flag?

Ah, I didn't realize they reused codes from ISO 3166-3. I figured, because they keep these regions around in their own set, that was some implication that the codes would not be reused.

Unicode doesn't define any flags, really. That's up to the font rendering on systems/libraries.

True, but Unicode explicitly defines "SU" as a deprecated combination, regardless of flags. Seems like they omit everything from the list of "no longer used" country codes, with some exceptions. I would think they would have no reason not to allow historical regions.