Still befuddled, but I'm glad someone gets it
Haha, okay. The codex is grouped per sector, and the galaxy is divided in 42 sectors. It'll show you the objects (e.g. 'supergiant Type F star' or 'earth-like world' or 'water geyser') in the sector you are currently in, and there are three possible 'states'. Lets take a black hole as an example.
1) Rumoured. This means noone has found a black hole yet in the sector, but FD told us there is at least one.
2) Reported. Some other player found a black hole in the sector, but you haven't. If you want to you can see where this other person found the first one, and go there yourself.
3) Confirmed. You have personally found a black hole in the sector (and that specific black hole may or may not have been discovered by someone else earlier, it is just the first black hole in the sector YOU found).
Now, if you 'confirm' an object that noone else had previously found there (so you find a black hole, and nobody else had found
any black hole in the
entire sector) not only does the status become 'confirmed' (because you found one) but your name is listed for all to see as the person who found the first black hole in the system. To be clear, finding a specific black hole nobody found before is not enough to get your name in the codex, it only happens if
nobody found
any kind of black hole in the
entire sector so you are literally the first one to show proof that kind of thing exists at all in the sector.
Lastly but importantly:
objects can exist without being listed in the codex. That means 1) Nobody found one yet, and 2) FD didn't tell us by listing it as 'rumoured'. As a result, the 'starting sector' (including the bubble) is the sector that has the most stuff in the codex. That doesnt mean there is more to find here, it just means we have already found a lot of stuff here, because the majority of people are in this sector.