Interesting, I always assumed it just meant derivatives had to be MIT as well, but it makes sense.
If I made changes to the software, would I just add myself to the Copyright list of authors?
If I made changes to the software, would I just add myself to the Copyright list of authors?
Here's a super-long answer:
You can if you want attribution. the problem with this is that the licenses refer to the "above copyright notice", and most people put the license in headers.
So as you might imagine, if you have 50 files, with different contributors, and they all list their names in the appropriate notices so that you have different notices on each file, well then, Congrats, now people using the software have to reproduce 50 notices!
This becomes a mess, and it also turns out that other than the license referring to it, the notice is legally pointless.
It is cargo cult lawyering to have copyright notices for legal reasons. It isn't required in any berne signatory country (all 168 of them: http://www.wipo.int/treaties/en/ShowResults.jsp?treaty_id=15). It has basically no legal usefulness[1]
As a result, the better practice is to just use something that is legally okay, but more inclusive.
This is why when chromium was released, i had them put "The chromium authors" as the copyright owner. It's legally correct/valid, but means nobody has to add stuff to it.
[1] In the US, it prevents the innocent infringement defense. But the innocent infringement defense requires that A. you bought a license B. from someone you reasonably believed owned the code because of the incorrect copyright notice
Because of the legal standard, I cannot find a single successful innocent infringement defense since Berne.
But it doesn't mean "claim it as your own", as long as it's not significantly altered.
No, you cannot relicense. Only the original authors can do that. You can add on top of the existing code stuff of your own under a different license, so that the combination of the two is under both licenses. Practically, it amounts to almost the same, but for example, you cannot remove conditions such as attribution, which only the original authors can do via a license that does not require attribution.
It depends what was meant by derivative and how this impacts the original code (encapsulated, modified, etc...). I was thinking more of when you use an MIT-licensed lib or 3rd party tool, or when you would reuse a code-snippet licensed as MIT and modify it. License and attributions remain, but only for that part of the code.
This is why a lot of projects (ie clojure) require some sort of contributor agreement so that the original authors can retain control while still accepting contributions.