> By looking at other code? Are you violating copyright when you are writing similar code yourself?
It's certainly possible. Back when Phoenix reverse-engineered the IBM BIOS using published sources with a restrictive license, they did it by having one team read the sources and write a very detailed specification of everything that happens there, and then another team used that spec to write new code from scratch. They did it that way because if the first team were to write the code themselves, it is quite likely that the result would be legally considered derived work.
It's certainly possible. Back when Phoenix reverse-engineered the IBM BIOS using published sources with a restrictive license, they did it by having one team read the sources and write a very detailed specification of everything that happens there, and then another team used that spec to write new code from scratch. They did it that way because if the first team were to write the code themselves, it is quite likely that the result would be legally considered derived work.