Yeah. I see that. So, back in 1850, they used a book / page system. Today, most, if not all, printed birth documents do not seem to reflect that book / page system. So far, no verified printed documents in aussie have been found with the book / page data. If I were to just guess, I would say that the book / page system was modified at some time.
But I did say before that I saw no evidence, and now someone showed it, so I can’t say that. I guess I can still say that I haven’t seen valid aussie printed birth docs with it.
I would think starting in the 80s and early 90s, or maybe even the late 70s for large government entities, registrars switched to computerized records. Can't say for sure, because I haven't personally looked for post-1960s government records - except for recent government records which are now often electronically available through the internet.