It is 35mm but I’ve never seen this kind of negative strip. I am scanning some old family negatives, probably 45 years old.
It has one sprocket hole per frame, only one one edge of the film. The frame markings are also different than anything I’ve ever seen. They scan just like other 35mm film but my scanner software can’t find the frames so I have to frame them manually.
Concur with @blondebear, I worked at a 1 hour photo lab during high school/university (86-93). 126 wasn’t a big deal for us, but I hated 110 and even worse Disc film. When making prints, you would look at the subject and adjust colour and density by hitting one or more keys eg +1D-2C0M0Y would reduce the Cyan and increase the exposure from what the sensors thought were correct. With 35mm I could print a whole roll in 60 seconds or so.
On the smaller negatives it was hard to make out the subject. A dog? A kid in a lake? The sky? So there were a lot more reprints when they came out the other end and had to reprint them.
I did not know one-hour labs used manual exposure settings. I just figured it was 100% automated unless you took it to a pro lab.
We’re going back 30+ years here, so no AI or anything fancy. There was a colorimeter and density meter built in, but we had to compensate for bad exposures and incorrect white balance. For example, you could see the green cast of fluorescent lights and would compensate by going + on the yellow. Outdoor pictures with people in the foreground would have the faces washed out unless we + density. We weren’t picking an exposure time, just offsetting what the scanner thought the settings should be.
Given the technology at the time, the human brain was probably faster and more accurate then the machine would be.