Hello KK.
There are quite a number of reasons for restricting public access to files, that have been assigned for safe keeping, to the NZ National Archives service. In this case I'm assuming it was due to the very fragile state of the record held.
Court files can be restricted due to the delicate nature of the contents.
Then in more recent years various, and updated, personal privacy legislation Acts have been set in place. So items are dependant upon the conditions imposed by the agency forwarding the records; relevant statute; and court Judge decisions, when assigned for safe keeping OR the latest legislation governing the operation of the State Archive system.
There are some records I was able to view in the 1970's that I would love to revisit with my camera, now that that is OK, but can not, due to more recent privacy Acts of Parliament.
Alan.
PS There is also another issue here in play, that those of us who supply research info to the forum have to keep in mind. While the governing conditions with regard to that type of School Register state access is available after 60 years following closure [reply# 9 ] this site is managed using the host country [UK] legislation. Why I noted that the image I posted was of a HISTORIC record. Over 100 years.
Added.. PSS. Another compounding factor when it comes to bound register books etc, and not individual correspondence or case files, the OPERATIVE date is AFTER the last entry. Some files I have accessed cover periods in excess of 30 years. If the items you want to see are dated pre WWI but the item / file was not closed until say 1940, you are interested in a RESTRICTED item, and must plead your case, with the assigning agency / department, for written permission to view.