I will rephrase the question. I do understand from this example that it is the next free slot, but the thing is that this document does not list all the existing forks, like GOLOS, CYBER, WHALESHARES etc. that were before the HIVE fork. Has HIVE blockchain registered, acquired or is in the process of getting this number, or it is just a dummy example?

OK, thanks. I got it. The keyword "for now" works for me. I take it as an example that is not yet production ready, since HIVE is not yet on the list.