I commonly hear people saying that, but then other people claiming this isn't true.
Is there a clear source for this mechanism?
Is there a clear source for this mechanism?
Incidentally, this is why Richard Stallman objects to the term intellectual property. It bundles together three very different areas of property rights (copyright, trademark, and patents) and treats them as sort of a single entity, even though they're really very different, both in their reason for existing and in their mechanisms.
People believe so many dumb things about copyright, trademark, patents, and trade secrets. For example: You don't legally need to use the various symbols for trademarks and copyrights you don't own. Unless there's a contract in force saying you have to, there's no Symbol Police gonna rappel from the skylights and break your keyboard if you say you used a Xerox without the nifty ™ symbol.
Another thing I've seen is the apparent notion that you can "renew" a copyright. Nope, not for a long time now: You get the full term up front with no special action, and once it's done it's gone, unless the law is actually changed in the meantime. Disney didn't "renew" the copyright on "Steamboat Willie" and the dumb live-action remakes aren't being done to "renew" anything, they're just some executive having a brain fart.
Like "Steamboat Willie", which I believe was mentioned here recently.
This issue with Notepad++ isn't even really about trademark, even though that would be the legal means to enforce it. It's more about Criteria #4 of the opensource definition "Integrity of The Author’s Source Code" Which is there so you can't give the original project a bad name while forking it. https://opensource.org/osd
[0] https://old.reddit.com/r/nintendo/comments/5m9grz/theres_no_...
There isn't a clear source (at least that I'm aware of) since this is handled by the legal system with a lot of nuance on a case by case basis. It is very reasonable to be proactive in trademark defense but if you aren't courts may still side with you if the establishment of usage was clear.