[jecel]

You are correct about the US in relation to trademarks. The situation there is rather complex, with it being possible for people to just add TM to their texts and ask other people to do the same and it is considered legally binding. They can take the extra step of registering and then they add (R) to their texts and that gets them an even stronger legal case.

Because of the case law nature of the US legal system and the informality of TM, if other people start using the term in other ways (for example using "xerox" as a verb meaning "copy") and you don't show an effort to curb that then you can lose your trademark.

In other countries things are different. Brazil, for example, uses a Latin legal system which is more formal. So the only thing that matters is whether you have registered the trademark with INPI (National Institute for Intellectual Property) or not. Which is why Gradiente owned the iPhone trademark in Brazil even though they were not using it anymore (it was from a product from around 2000) and if you asked anybody on the streets in Brazil they would associate the name with Apple.