[bayindirh]

A trademark changes the situation in every aspect. If your code is getting big, famous, and needs its name and likeness (e.g. Firefox), you get a trademark, and your derivatives shall not use the name. It's simple and clear.

When I quickly looked, bzip2 didn't have a trademark, and I assumed the developer don't care.

It's same for me. If I care, I'd trademark it, and prevent people from using it. If I'm giving the name away, I'd not trademark it. It's plain and simple.

[eru]

So, a trademark is a 'legal' concept, and comes with certain rights and obligations. Eg you need to actively defend your trademark in order to keep it.

I was perhaps a bit fuzzy: I used the word trademark, but I meant the moral equivalent that only confers moral rights and obligations. Ie don't be a jerk and name your stuff in a confusing way, even if there's no legal obligation.

Even this fuzzier 'moral' trademark only applies, if the original owner wants it to apply. I have no special insight into the bzip2 situation. So I have no clue whether the authors of bzip or bzip2 cared. I gladly defer to your research on this question.

My point was meant purely abstract about the possibility of wanting your source to be free and open and fondled by others, but still have a (morally) protected name.