[dn3500]

Engineering notebooks were required at my first job in the 1970s, for patent reasons. The notebook pages are numbered and it has a real sewn binding, making it harder to remove or insert a page without being noticed. We were required to date and sign each page and start a new page every day.

By the time I retired I think I was the only one at my company using one. I had to special order to get a proper one with the quad ruling, numbered pages, and sewn binding.