In the website of Switzerland, they call the D visa in Switzerland long-term national visa, but the validity they offered was exactly 90 days (from 06/02/2024 to 05/05/2024).
That seems very dumb. A short stay in the Schengen system is a stay of 90 days or less (originally 3 months). I don't think that's explicitly defined anywhere but that's the threshold used all over the place and it necessarily follows that a long stay is a stay for more than 90 days. Issuing a visa that falls just under that threshold is utterly confusing and calling it a “long-term” visa achieves nothing (it's up to the Schengen acquis/EU law, not to each individual country, to define what's long term).
The important thing from Norway's perspective is that the visa exemption when crossing an external border defined in article 6(1)(b) only applies to “a valid residence permit or a valid long-stay visa”. It doesn't define or mention “national visas” or “type D visas” but it is clearly limited to long-stay visas, which ought to mean visas for stays longer than 90 days.
That said, I don't think that the Immigration Office of Norway necessarily meant to distinguish between different types of D visas, as opposed to simply assuming they would be valid for more than 90 days as national short-stay visas are not foreseen by the Schengen system (otherwise all the requirements and the whole architecture of the regulations would be entirely optional). These would in any case be very rare.
Because of all this it's unfortunately hard to determine how this visa should be treated or guess how border guards might look at it.
