What is the meaning of pg_restore output?

I have questions about pg_restore output.

and aren't present when -j 1 (or without -j)

So main questions are:

1. What is the meaning of this phrases?

2. Are they documented somewhere?

3. Is it possible that output change from version to version?

Why I am asking?

I saw a script which does pg_restore and grep some of this phrases as SUCCESS indicator that pg_restore passed OK (+ something like grep -iv "error").

script doesn't use pg_restore exit code because, as I understood from the authors, in the past were situations that pg_restore returned 0 code but didn't restore of db.

Any answers, hints are welcome :).

Thanks